Blender 4.x / 5.2 compatibility

[051jeferson]

Summary

This PR makes Cats Blender Plugin 0.19.0 load and run on modern Blender, including Blender 5.2.

The upstream release still targets older Blender APIs and currently fails / misbehaves on current versions. These changes keep older Blender paths where possible and guard APIs that were removed or replaced.

What changed

• Removed / replaced Blender APIs
  • Bone layers / pose bone groups → safe fallbacks and bone collections on Blender 4.0+
  • Pose libraries skipped when unavailable
  • mesh.use_auto_smooth guarded (removed in 4.1+)
  • �ddon_support no longer includes TESTING (removed in 4.2+)
  • Scene/bone layer checks only when those attributes exist
• Threading / UI safety
  • Updater, supporter, and settings background work deliver results via �py.app.timers on the main thread
  • Timers stopped cleanly on unregister
• Python correctness
  • Fixed invalid string escapes (\Left / \L → \Left / \L) and regex patterns
• Tests
  • Added Blender 5.2 smoke / operator audit helpers

Testing

• Verified on Blender 5.2 (Windows)
• Addon enables, UI loads, and core operators were audited with the added helper scripts

Notes

• Version remains .19.0 to stay aligned with the current release line.
• Happy to split / adjust anything maintainers prefer (e.g. target development instead of master).

Thanks for maintaining CATS!

[051jeferson]

Note on versioning (fork distribution): this branch also bumps the visible addon version to 0.20.0 and renames the add-on to Cats Blender Plugin (5.2) so users can tell it apart from official 0.19.0.

If maintainers prefer to keep 0.19.0 on merge, I can split the version/branding changes out and leave only the API compatibility fixes here.

[RinaDev-xyz]

This repo has been abandoned please see: #720 so this will never get merged.

There several forks and I have made 100s of improvements and changes myself on my version.

Thanks.