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/MeshRadio.h

@@ -64,8 +64,14 @@
 class MeshRadio
 {
   public:
+    // Kinda ugly way of selecting different radio implementations, but soon this MeshRadio class will be going away
+    // entirely.  At that point we can make things pretty.
+#ifdef RF95_IRQ_GPIO
     CustomRF95
-        rf95; // the raw radio interface - for now I'm leaving public - because this class is shrinking to be almost nothing
+        radioIf; // the raw radio interface - for now I'm leaving public - because this class is shrinking to be almost nothing
+#else
+    SimRadio radioIf;
+#endif
 
     /** pool is the pool we will alloc our rx packets from
      * rxDest is where we will send any rx packets, it becomes receivers responsibility to return packet to the pool
@@ -88,14 +94,8 @@ class MeshRadio
 
   private:
     // RHReliableDatagram manager; // don't use mesh yet
-    RHMesh manager;
+    // RHMesh manager;
 
     /// Used for the tx timer watchdog, to check for bugs in our transmit code, msec of last time we did a send
     uint32_t lastTxStart = 0;
-
-    /// low level send, might block for mutiple seconds
-    ErrorCode sendTo(NodeNum dest, const uint8_t *buf, size_t len);
-
-    /// enqueue a received packet in rxDest
-    void handleReceive(MeshPacket *p);
 };