add beginnings of nodedb

src/MeshTypes.h

@@ -0,0 +1,13 @@
+#pragma once
+
+// low level types 
+
+#include <Arduino.h>
+
+typedef uint8_t NodeNum;
+
+#define NODENUM_BROADCAST 255
+#define ERRNO_OK 0
+#define ERRNO_UNKNOWN 32 // pick something that doesn't conflict with RH_ROUTER_ERROR_UNABLE_TO_DELIVER
+
+typedef int ErrorCode;