Support differentiating between portable & system installations,
useful to properly locate relative paths which would not work
on system installations.
Ref !133143
BaseException was used as a catch-all in situations where it
didn't make sense and where "Exception" is more appropriate
based on Python's documentation & error checking tools,
`pylint` warns `broad-exception-caught` for e.g.
BaseException includes SystemExit, KeyboardInterrupt & GeneratorExit,
so unless the intention is to catch calls to `sys.exit(..)`,
breaking a out of a loop using Ctrl-C or generator-exit,
then it shouldn't be used.
Even then, it's preferable to catch those exceptions explicitly.
Expose arguments to use when creating a Python sub-process.
Python could fail to start when loaded in a customized environment,
with PYTHONPATH set for e.g. Blender ignores these and loads but a
Python sub-process attempts to use these environment variables which
may point to incompatible Python versions.
Resolve the root cause of #124731.
Support freedesktop file association on Linux/Unix via the command line
arguments: `--register{-allusers}` `--unregister{-allusers}` as well
registration actions from the user preferences.
Once registered, the "Blender" application is available from launchers
and `*.blend` files are assoisated with the blender binary used for
registration.
The following operations are performed:
- Setup the desktop file.
- Setup the file association & make it default.
- Copy the icon.
- Setup the thumbnailer (`--register-allusers` only).
Notes:
- Registering/unregistering for all users manipulates files under
`/usr/local` and requires running Blender as root.
From the command line this can be done using `sudo`, e.g.
`sudo ./blender --register-allusers`.
From the GUI, the `pkexec` command is used.
- Recent versions of GNOME execute the thumbnailer in a restricted
environment (`bwrap`) requiring `blender-thumbnailer` to be copied
into `/usr/local/bin` (synlinks don't work).
So thumbnailing copies the binary rather than linking and only works
when registering for all users.
Ref !120283
