Switch to '#!/usr/bin/env python3' shebang lines

Since the Docker build image runs a python virtual environment now.

Also added 'scripts/runDocker' script which will invoke docker locally
with the same image used in Github CI, for testing.

Note this script will pull over a GB of Docker stuff onto the machine
it's invoked on, if the image is not already cached.

scripts/apiconventions.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2021-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/cgenerator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/checklinks.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/clconventions.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/docgenerator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/extensionmetadocgenerator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/genRef.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #
 # Copyright 2016-2024 The Khronos Group Inc.
 #

scripts/gen_dictionaries.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 # Copyright 2019-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/gen_version_notes.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 # Copyright 2019-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/gencl.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/generator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/parse_dependency.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 # Copyright 2022-2024 The Khronos Group Inc.
 # Copyright 2003-2019 Paul McGuire

scripts/pygenerator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/realign.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 # SPDX-License-Identifier: Apache-2.0

scripts/reflib.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 #
 # Copyright 2016-2024 The Khronos Group Inc.
 #

scripts/reg.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/runDocker

@@ -0,0 +1,30 @@
+#!/bin/bash
+# Copyright 2022-2024 The Khronos Group Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+# runDocker - run the Khronos `asciidoctor-spec` Docker image with a local
+# clone of the specification repository.
+# The following command-line tools are required to run this script:
+#   awk dirname docker grep id realpath
+# These are all normal Linux developer tools except for 'docker' itself.
+
+# Determine path to repository root directory
+scriptpath=`dirname $0`
+repopath=`realpath $scriptpath/..`
+
+# Get SHA256 of the asciidoctor-spec image build used by CI.
+image=`grep -m 1 khronosgroup/docker-images@sha256: $repopath/.github/workflows/presubmit.yml | \
+    awk '{print $2}'`
+
+uid=`id -u`
+gid=`id -g`
+echo "Executing Docker with spec build image and mounted spec repository root:"
+
+# --user causes Docker to run as the specified UID:GID instead of as root
+# -it runs interactively and uses a pseudotty
+# --rm removes the container on exit
+# -v mounts the repository clone as /vulkan in the container
+# $image is image to run
+# /bin/bash drops into a shell in the container
+set -x
+docker run --network=host --user ${uid}:${gid} -it --rm -v ${repopath}:/opencl $image /bin/bash

scripts/scriptgenerator.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #

scripts/spec_tools/conventions.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python3 -i
+#!/usr/bin/env python3 -i
 #
 # Copyright 2013-2024 The Khronos Group Inc.
 #