- remove unused members from BMBVHTree - move per-raycast vars from BMBVHTree into per-callback structs (weren't threadsafe). - simplify BKE_bmbvh_find_vert_closest().
- remove unused members from BMBVHTree - move per-raycast vars from BMBVHTree into per-callback structs (weren't threadsafe). - simplify BKE_bmbvh_find_vert_closest().