Examples: Python ShellBang & Executable (#2673)

* Examples: Python ShellBang & Executable

Make sure that all PICMI scripts and all analysis Python scripts
in `Examples/` are:
- executable (`chmod a+x`)
- start with a shell-bang to `python3`

Now, all scripts can be run directly without a `python3 ...` prefix
and also default to the only right executable of Python on older
systems. (New systems always have a `python3` alias, too.)

* Revert a moved numpy

29 files changed, 35 insertions, 25 deletions

diff --git a/Examples/Modules/ParticleBoundaryProcess/PICMI_inputs_reflection.py b/Examples/Modules/ParticleBoundaryProcess/PICMI_inputs_reflection.py
index b6d9e6cf6..f6be14e5a 100644..100755
--- a/Examples/Modules/ParticleBoundaryProcess/PICMI_inputs_reflection.py
+++ b/Examples/Modules/ParticleBoundaryProcess/PICMI_inputs_reflection.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+#
 # --- Input file to test particle reflection off an absorbing boundary
 
 from pywarpx import picmi
diff --git a/Examples/Modules/ParticleBoundaryProcess/analysis_absorption.py b/Examples/Modules/ParticleBoundaryProcess/analysis_absorption.py
index cb6595c78..f9a44f22c 100755
--- a/Examples/Modules/ParticleBoundaryProcess/analysis_absorption.py
+++ b/Examples/Modules/ParticleBoundaryProcess/analysis_absorption.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 import yt
 
diff --git a/Examples/Modules/ParticleBoundaryProcess/analysis_reflection.py b/Examples/Modules/ParticleBoundaryProcess/analysis_reflection.py
index 7dbb26206..1fa141bcd 100755
--- a/Examples/Modules/ParticleBoundaryProcess/analysis_reflection.py
+++ b/Examples/Modules/ParticleBoundaryProcess/analysis_reflection.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2021 Modern Electron
 #
diff --git a/Examples/Modules/ParticleBoundaryScrape/PICMI_inputs_scrape.py b/Examples/Modules/ParticleBoundaryScrape/PICMI_inputs_scrape.py
index 99dd2ffab..3158949bc 100644..100755
--- a/Examples/Modules/ParticleBoundaryScrape/PICMI_inputs_scrape.py
+++ b/Examples/Modules/ParticleBoundaryScrape/PICMI_inputs_scrape.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+#
 # --- Input file to test the particle scraper and the Python wrappers
 # --- to access the buffer of scraped particles.
 
diff --git a/Examples/Modules/ParticleBoundaryScrape/analysis_scrape.py b/Examples/Modules/ParticleBoundaryScrape/analysis_scrape.py
index c325495db..652fd3be3 100755
--- a/Examples/Modules/ParticleBoundaryScrape/analysis_scrape.py
+++ b/Examples/Modules/ParticleBoundaryScrape/analysis_scrape.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 import yt
 from pathlib import Path
diff --git a/Examples/Modules/RigidInjection/analysis_rigid_injection_BoostedFrame.py b/Examples/Modules/RigidInjection/analysis_rigid_injection_BoostedFrame.py
index 9e97f28ff..5e5a5bf74 100755
--- a/Examples/Modules/RigidInjection/analysis_rigid_injection_BoostedFrame.py
+++ b/Examples/Modules/RigidInjection/analysis_rigid_injection_BoostedFrame.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Luca Fedeli, Maxence Thevenet, Revathi Jambunathan
 #
diff --git a/Examples/Modules/RigidInjection/analysis_rigid_injection_LabFrame.py b/Examples/Modules/RigidInjection/analysis_rigid_injection_LabFrame.py
index 2c97483fd..5038ecc21 100755
--- a/Examples/Modules/RigidInjection/analysis_rigid_injection_LabFrame.py
+++ b/Examples/Modules/RigidInjection/analysis_rigid_injection_LabFrame.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Luca Fedeli, Maxence Thevenet
 #
diff --git a/Examples/Modules/boosted_diags/analysis_3Dbacktransformed_diag.py b/Examples/Modules/boosted_diags/analysis_3Dbacktransformed_diag.py
index eac8e4ae9..2dac6d245 100755
--- a/Examples/Modules/boosted_diags/analysis_3Dbacktransformed_diag.py
+++ b/Examples/Modules/boosted_diags/analysis_3Dbacktransformed_diag.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019 Maxence Thevenet, Revathi Jambunathan
 #
diff --git a/Examples/Modules/dive_cleaning/analysis.py b/Examples/Modules/dive_cleaning/analysis.py
index a2cdffc6f..c4c09353e 100755
--- a/Examples/Modules/dive_cleaning/analysis.py
+++ b/Examples/Modules/dive_cleaning/analysis.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Axel Huebl, Remi Lehe
 #
diff --git a/Examples/Modules/embedded_boundary_cube/analysis_fields.py b/Examples/Modules/embedded_boundary_cube/analysis_fields.py
index 9abd8579e..05f43ce1c 100755
--- a/Examples/Modules/embedded_boundary_cube/analysis_fields.py
+++ b/Examples/Modules/embedded_boundary_cube/analysis_fields.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 import yt
 import os, sys
diff --git a/Examples/Modules/embedded_boundary_cube/analysis_fields_2d.py b/Examples/Modules/embedded_boundary_cube/analysis_fields_2d.py
index ebf303601..8127cc9e5 100755
--- a/Examples/Modules/embedded_boundary_cube/analysis_fields_2d.py
+++ b/Examples/Modules/embedded_boundary_cube/analysis_fields_2d.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 import yt
 import os
diff --git a/Examples/Modules/embedded_boundary_python_API/PICMI_inputs_EB_API.py b/Examples/Modules/embedded_boundary_python_API/PICMI_inputs_EB_API.py
index bc56968d2..e350ce414 100644..100755
--- a/Examples/Modules/embedded_boundary_python_API/PICMI_inputs_EB_API.py
+++ b/Examples/Modules/embedded_boundary_python_API/PICMI_inputs_EB_API.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 from pywarpx import picmi, _libwarpx, fields
 import numpy as np
 
diff --git a/Examples/Modules/embedded_boundary_python_API/analysis.py b/Examples/Modules/embedded_boundary_python_API/analysis.py
index b6b2955cf..09cc2accf 100755
--- a/Examples/Modules/embedded_boundary_python_API/analysis.py
+++ b/Examples/Modules/embedded_boundary_python_API/analysis.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # This script just checks that the PICMI file executed successfully.
 # If it did there will be a plotfile for the final step.
diff --git a/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields.py b/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields.py
index 7765c5d69..655322b5b 100755
--- a/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields.py
+++ b/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2021 Lorenzo Giacomel
 #
diff --git a/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields_2d.py b/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields_2d.py
index cde45e596..2b48d1a36 100755
--- a/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields_2d.py
+++ b/Examples/Modules/embedded_boundary_rotated_cube/analysis_fields_2d.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 import yt
 import os
diff --git a/Examples/Modules/gaussian_beam/PICMI_inputs_gaussian_beam.py b/Examples/Modules/gaussian_beam/PICMI_inputs_gaussian_beam.py
index 710b78bd5..a20f18a68 100644..100755
--- a/Examples/Modules/gaussian_beam/PICMI_inputs_gaussian_beam.py
+++ b/Examples/Modules/gaussian_beam/PICMI_inputs_gaussian_beam.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 from pywarpx import picmi
 #from warp import picmi
 import argparse
diff --git a/Examples/Modules/ionization/analysis_ionization.py b/Examples/Modules/ionization/analysis_ionization.py
index 03b1d5513..8b0670fdc 100755
--- a/Examples/Modules/ionization/analysis_ionization.py
+++ b/Examples/Modules/ionization/analysis_ionization.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Luca Fedeli, Maxence Thevenet
 #
diff --git a/Examples/Modules/laser_injection/analysis_1d.py b/Examples/Modules/laser_injection/analysis_1d.py
index 6606938df..7c8e985f6 100755
--- a/Examples/Modules/laser_injection/analysis_1d.py
+++ b/Examples/Modules/laser_injection/analysis_1d.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2021 Prabhat Kumar, Remi Lehe
 #
diff --git a/Examples/Modules/laser_injection/analysis_2d.py b/Examples/Modules/laser_injection/analysis_2d.py
index fffa7d3a1..1ea477dbd 100755
--- a/Examples/Modules/laser_injection/analysis_2d.py
+++ b/Examples/Modules/laser_injection/analysis_2d.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019 Andrew Myers, Jean-Luc Vay, Maxence Thevenet
 # Remi Lehe, Weiqun Zhang, Luca Fedeli
diff --git a/Examples/Modules/laser_injection/analysis_laser.py b/Examples/Modules/laser_injection/analysis_laser.py
index 1e4f3daf7..e2ed2e1bb 100755
--- a/Examples/Modules/laser_injection/analysis_laser.py
+++ b/Examples/Modules/laser_injection/analysis_laser.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019 Andrew Myers, Jean-Luc Vay, Maxence Thevenet
 # Remi Lehe, Weiqun Zhang
diff --git a/Examples/Modules/nci_corrector/analysis_ncicorr.py b/Examples/Modules/nci_corrector/analysis_ncicorr.py
index af23f15ed..409c4ba2f 100755
--- a/Examples/Modules/nci_corrector/analysis_ncicorr.py
+++ b/Examples/Modules/nci_corrector/analysis_ncicorr.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019 Jean-Luc Vay, Maxence Thevenet, Remi Lehe
 # Weiqun Zhang
diff --git a/Examples/Modules/qed/breit_wheeler/analysis_core.py b/Examples/Modules/qed/breit_wheeler/analysis_core.py
index 4e17676a2..cb65fccb9 100644..100755
--- a/Examples/Modules/qed/breit_wheeler/analysis_core.py
+++ b/Examples/Modules/qed/breit_wheeler/analysis_core.py
@@ -1,9 +1,11 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
 # Copyright 2019 Luca Fedeli, Maxence Thevenet
 #
 # This file is part of WarpX.
 #
 # License: BSD-3-Clause-LBNL
-# -*- coding: utf-8 -*-
 
 import numpy as np
 import scipy.special as spe
diff --git a/Examples/Modules/qed/breit_wheeler/analysis_opmd.py b/Examples/Modules/qed/breit_wheeler/analysis_opmd.py
index cbdd8e6e8..be86f2dd5 100755
--- a/Examples/Modules/qed/breit_wheeler/analysis_opmd.py
+++ b/Examples/Modules/qed/breit_wheeler/analysis_opmd.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2019 Luca Fedeli
 #
 # This file is part of WarpX.
diff --git a/Examples/Modules/qed/breit_wheeler/analysis_yt.py b/Examples/Modules/qed/breit_wheeler/analysis_yt.py
index 1d9c90691..47b6a3428 100755
--- a/Examples/Modules/qed/breit_wheeler/analysis_yt.py
+++ b/Examples/Modules/qed/breit_wheeler/analysis_yt.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2019 Luca Fedeli
 #
 # This file is part of WarpX.
diff --git a/Examples/Modules/qed/quantum_synchrotron/analysis.py b/Examples/Modules/qed/quantum_synchrotron/analysis.py
index 2efefc219..a38aff595 100755
--- a/Examples/Modules/qed/quantum_synchrotron/analysis.py
+++ b/Examples/Modules/qed/quantum_synchrotron/analysis.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019 Luca Fedeli, Maxence Thevenet
 #
diff --git a/Examples/Modules/qed/schwinger/analysis_schwinger.py b/Examples/Modules/qed/schwinger/analysis_schwinger.py
index 938e03271..33e82652d 100755
--- a/Examples/Modules/qed/schwinger/analysis_schwinger.py
+++ b/Examples/Modules/qed/schwinger/analysis_schwinger.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2020 Luca Fedeli, Neil Zaim
 #
diff --git a/Examples/Modules/relativistic_space_charge_initialization/analysis.py b/Examples/Modules/relativistic_space_charge_initialization/analysis.py
index fc1a169ef..66c47cca6 100755
--- a/Examples/Modules/relativistic_space_charge_initialization/analysis.py
+++ b/Examples/Modules/relativistic_space_charge_initialization/analysis.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Axel Huebl, Remi Lehe
 #
diff --git a/Examples/Modules/resampling/analysis_leveling_thinning.py b/Examples/Modules/resampling/analysis_leveling_thinning.py
index a9e8f380d..32e85d2c5 100755
--- a/Examples/Modules/resampling/analysis_leveling_thinning.py
+++ b/Examples/Modules/resampling/analysis_leveling_thinning.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2020 Neil Zaim
 #
diff --git a/Examples/Modules/space_charge_initialization/analysis.py b/Examples/Modules/space_charge_initialization/analysis.py
index b13b9d3fe..feb965733 100755
--- a/Examples/Modules/space_charge_initialization/analysis.py
+++ b/Examples/Modules/space_charge_initialization/analysis.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright 2019-2020 Axel Huebl, Remi Lehe
 #