Flamenco now no longer uses the Git tags + hash for the application
version, but an explicit `VERSION` variable in the `Makefile`.
After changing the `VERSION` variable in the `Makefile`, run
`make update-version`.
Not every part of Flamenco looks at this variable, though. Most
importantly: the Blender add-on needs special handling, because that
doesn't just take a version string but a tuple of integers. Running
`make update-version` updates the add-on's `bl_info` dict with the new
version. If the version has any `-blabla` suffix (like `3.0-beta0`) it
will also set the `warning` field to explain that it's not a stable
release.
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.
