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.

sim/platform_linux.h

@@ -0,0 +1,16 @@
+#ifdef platform_h
+#error "platform implementation already defined"
+#else
+
+#include <pthread.h>
+
+
+typedef struct {
+  pthread_t tid;
+  int exit;
+} plat_thread_t;
+
+typedef void*(*plat_threadfunc_t)(void*);
+#define PLAT_THREAD_FUNC(name,arg) void* name(void* arg)
+
+#endif