poll workers for non-threaded support, emscripten main loop, remove twn_model.c

src/rendering/twn_models.c

@@ -162,7 +162,7 @@ void draw_model(const char *model,
         };
         arrpush(model_load_queue, request);
         SDL_UnlockMutex(model_load_mutex);
-        SDL_SemPost(workers_job_semaphore);
+        workers_add_job();
     } else
         modelcopy = item->key;