Blendshapes without a skeleton already worked.
However, due to a faulty ERR_FAIL_COND, it was impossible to create a mesh with both bones and blendshapes.
This also fixes an assumption that all surfaces reference the same number of bones as surface 0.
-Happens on import by default for all models
-Just works (tm)
-Biasing can be later adjusted per node or per viewport (as well as globally)
-Disabled AABB.get_support test because its broken
We haven't had a proper implementation for COMPRESS_PVRTC2 (which is PVRTC1 2-bpp) in years,
so let's drop it instead of keeping a compress type which doesn't work.
The other enum values were renamed to clarify that our PVRTC2 and PVRTC4 are respectively
PVRTC1 2-bpp and PVRTC1 4-bpp. PVRTC2 2-bpp and 4-bpp are not implemented yet.