The getter of this matrix (actually, `BKE_object_matrix_local_get()`) was only correct
in case of pure-object parenting, bone parenting and such did not gave valid results.
Also cleaned up a bit setter code, was using as temp storage ob->obmat itself,
which is supposed to be a world matrix!
Reviewers: campbellbarton
Reviewed By: campbellbarton
Differential Revision: https://developer.blender.org/D958
fb7ff31315