begin cleanup on radio abstraction, details below:

* to allow changing to new mesh transport
* to allow a different chipset for the radio
* to allow testing on hardware with a SimRadio
* new "bare" build env for a devboard with virtually no hardware
* make buttons optional

src/RadioInterface.cpp

@@ -0,0 +1,15 @@
+#include "CustomRF95.h"
+#include "NodeDB.h"
+#include "assert.h"
+#include "configuration.h"
+#include <pb_decode.h>
+#include <pb_encode.h>
+
+RadioInterface::RadioInterface(MemoryPool<MeshPacket> &_pool, PointerQueue<MeshPacket> &_rxDest) : pool(_pool), rxDest(_rxDest) {}
+
+ErrorCode SimRadio::send(MeshPacket *p)
+{
+    DEBUG_MSG("SimRadio.send\n");
+    pool.release(p);
+    return ERRNO_OK;
+}