Split "executable" from "its arguments" in blender & ffmpeg commands.
Use `{blenderArgs}` variable to hold the default Blender arguments,
instead of having both the executable and its arguments in `{blender}`.
The reason for this is to support backslashes in the Blender executable
path. These were interpreted as escape characters by the shell lexer.
The shell lexer based splitting is now only performed on the default
arguments, with the result that `C:\Program Files\Blender
Foundation\3.3\blender.exe` is now a valid value for `{blender}`.
This does mean that this is backward incompatible change, and that it
requires setting up Flamenco Manager again, and that older jobs will not
be able to be rerun.
It is recommended to remove `flamenco-manager.yaml`, restart Flamenco
Manager, and reconfigure via the setup assistant.
Prepare the Worker for submission of last-rendered images to Manager, by
parsing `stdout` of Blender to see which files were saved.
This needs more work, as now just an error "not implemented" is logged.
The add-on code was copy-pasted from other addons and used the GPL v2
license, whereas by accident the LICENSE text file had the GNU "Affero" GPL
license v3 (instead of regular GPL v3).
This is now all streamlined, and all code is licensed as "GPL v3 or later".
Furthermore, the code comments just show a SPDX License Identifier
instead of an entire license block.
