Total rework of simulator for dev branch. Create separate thread for interrupt processes. Tick-accurate simulation of timers. Non-blocking character input for running in realtime mode. Decouple hardware sim from grbl code as much as possible. Expanded command line options. Provisions for cross-platform solution.

serial.c

@@ -178,6 +178,7 @@ ISR(SERIAL_RX)
         #endif
         
       }
+		//TODO: some sort of alarm on overflow?
   }
 }