Was flipping around the 0-1 range, now (optionally) flip around each tile.
Also added this option for BMesh bmo_mirror.
Reviewed By: campbellbarton
Maniphest Tasks: T75793
Differential Revision: https://developer.blender.org/D7460
- Use 'BKE_object_defgroup' prefix for object functions.
- Rename 'defvert_verify_index' to 'defvert_ensure_index'
since this adds the group if it isn't found.