begin cleaning up mesh library layer so that it could be split someday

src/mesh/MeshTypes.h

@@ -0,0 +1,20 @@
+#pragma once
+
+// low level types
+
+#include "MemoryPool.h"
+#include "mesh.pb.h"
+#include <Arduino.h>
+
+typedef uint8_t NodeNum;
+typedef uint8_t PacketId; // A packet sequence number
+
+#define NODENUM_BROADCAST 255
+#define ERRNO_OK 0
+#define ERRNO_NO_INTERFACES 33
+#define ERRNO_UNKNOWN 32 // pick something that doesn't conflict with RH_ROUTER_ERROR_UNABLE_TO_DELIVER
+
+typedef int ErrorCode;
+
+/// Alloc and free packets to our global, ISR safe pool
+extern MemoryPool<MeshPacket> packetPool;