Cleaned up Dyntopo original triangle API (which is deprecated):
* BMVerts for original triangles are now stored.
* BKE_pbvh_bmesh_update_topology now handles original triangle
* data properly.
* BKE_pbvh_bmesh_node_save_orig can now initialize the original
coordinates from the current BMLogEntry.
* Ray casting of original data now returns active vertex.
Should fix various random crashes.
Hopefully this will fix a number of bugs.
7f133b7a38