Add empty wrapper for RtInternal struct.
Move close() method to top of WDB class.
Add ctypedef for mat_t.
Add wrappers for wdb_import and wdb_put_internal.
Add WDB.apply_mat() that calls import_ then put_internal to modify an object.
Add wrappers for some matrix macros.
Change _check_res to treat only negative values as error.
Make _check_res include the error value in the raised exception.
Add brlcad.set_mat_deltas(). Also, expect matrices to be numpy arrays
(in other functions, too).
Add BrlCadObject.move().