The old version is now accessed via center of area. This version works best
with manifold meshes, but will work in general with non-manifold meshes,
but will not be accurate. Even zero-area faces do not cause problems. Also,

it does not completely fall over when given a planar object with 0 volume.

source/blender/blenkernel/BKE_mesh.h | 1 +
source/blender/blenkernel/intern/mesh_evaluate.c | 72 ++++++++++++++++++++++++
source/blender/editors/object/object_transform.c | 6 +-
3 files changed, 78 insertions(+), 1 deletion(-)