Introduce __attribute__((unused)) (#defined to UNUSED_ATTR) to mark possibly unused paramters in functions, removing the need to do "(void)var;" to reduce compiler warnings and giving better readable code.
Adapt plugins to use it.
-change all plugin_start() to plugin_start(UNUSED_ATTR const void* parameter) and remove the (void)parameter.
-change cleanup functions passed to default_event_handler_ex to be "static void cleanup(UNUSED_ATTR void* paramter)"
-I didn't change importet code, that may still do (void)var; I didn't change custom callbacks or callbacks for other core (list callback, event callback) functions yet.
Unless -Ox is passed to gcc, this should also give a decent binsize reduce.