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

src/twn_workers_c.h

@@ -7,11 +7,10 @@
 
 #define MAX_WORKERS 9
 
-/* workers are waiting on this, increment this value when some work needs to be done */
-/* for now every possible job path is hardcoded in twn_workers.c itself */
-extern SDL_sem *workers_job_semaphore;
-
 bool workers_init(size_t worker_count);
 void workers_deinit(void);
+void workers_add_job(void);
+/* for targets lacking threading support main thread could do the work */
+void workers_poll(void);
 
 #endif