More rendering subsystem breakout, added a physics subsystem, everything now fires from akgl_game_update() for the user

src/registry.c

@@ -39,6 +39,9 @@ akerr_ErrorContext *akgl_registry_init()
 akerr_ErrorContext *akgl_registry_init_actor()
 {
     PREPARE_ERROR(errctx);
+    if ( AKGL_REGISTRY_ACTOR != NULL ) {
+	SDL_DestroyProperties(AKGL_REGISTRY_ACTOR);
+    }
     AKGL_REGISTRY_ACTOR = SDL_CreateProperties();
     FAIL_ZERO_RETURN(errctx, AKGL_REGISTRY_ACTOR, AKERR_NULLPOINTER, "Error initializing actor registry");
     SUCCEED_RETURN(errctx);