fix for assert(), were not enough mathutils slots.

source/blender/python/mathutils/mathutils.c

@@ -340,7 +340,7 @@ int mathutils_deepcopy_args_check(PyObject *args)
 /* Mathutils Callbacks */
 
 /* for mathutils internal use only, eventually should re-alloc but to start with we only have a few users */
-#define MATHUTILS_TOT_CB 10
+#define MATHUTILS_TOT_CB 13
 static Mathutils_Callback *mathutils_callbacks[MATHUTILS_TOT_CB] = {NULL};
 
 unsigned char Mathutils_RegisterCallback(Mathutils_Callback *cb)