Previously BPY_python_end wasn't called when scripts called sys.exit()
because BPY_python_end exited the Python interpreter.
Change this behavior to call BPY_python_end without exiting the Python
interpreter while freeing Blender/Python data.
While leaks in the context of sys.exit aren't especially important
it's generally preferable for sys.exit() to match Blender's code-paths
for exiting to avoid unexpected behavior.
Some of the comments for exiting were outdated & vague.
Add additional comments to clarify out SystemExit, sys.exit() & atexit
are used to handle exit requests from Python within Blender.
Listing the "Blender Foundation" as copyright holder implied the Blender
Foundation holds copyright to files which may include work from many
developers.
While keeping copyright on headers makes sense for isolated libraries,
Blender's own code may be refactored or moved between files in a way
that makes the per file copyright holders less meaningful.
Copyright references to the "Blender Foundation" have been replaced with
"Blender Authors", with the exception of `./extern/` since these this
contains libraries which are more isolated, any changed to license
headers there can be handled on a case-by-case basis.
Some directories in `./intern/` have also been excluded:
- `./intern/cycles/` it's own `AUTHORS` file is planned.
- `./intern/opensubdiv/`.
An "AUTHORS" file has been added, using the chromium projects authors
file as a template.
Design task: #110784
Ref !110783.
While these warnings point to real errors in the code,
PyMethodDef are an exception where functions with different numbers
of arguments are all cast to the same function type.
