- 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.
This adds a new mode to solidify to support non-manifold geometry
with edges using 3 or more faces as input, resulting in a manifold mesh.
Since the differences between these methods don't translate well
into short terms, they're named "Simple" and "Complex" in the UI.
This also adds clamp with respect to angles
to the existing solidify modifier calculation.
