WIP - add new baseclass for all api endpoints (serial, bluetooth, udp)

https://github.com/meshtastic/Meshtastic-esp32/issues/69

src/PhoneAPI.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include "mesh-pb-constants.h"
+#include "mesh.pb.h"
+#include <string>
+
+/**
+ * Provides our protobuf based API which phone/PC clients can use to talk to our device
+ * over UDP, bluetooth or serial.
+ *
+ * Eventually there should be once instance of this class for each live connection (because it has a bit of state
+ * for that connection)
+ */
+class PhoneAPI
+{
+    enum State {
+        STATE_SEND_NOTHING, // Initial state, don't send anything until the client starts asking for config
+        STATE_SEND_MY_NODEINFO,
+        STATE_SEND_OWNER,
+        STATE_SEND_RADIO,
+        STATE_SEND_COMPLETE_ID,
+        STATE_SEND_PACKETS // send packets or debug strings
+    };
+
+    State state = STATE_SEND_NOTHING;
+
+    /**
+     * Each packet sent to the phone has an incrementing count
+     */
+    uint32_t fromRadioNum = 0; 
+
+  public:
+    PhoneAPI();
+
+    /**
+     * Handle a ToRadio protobuf
+     */
+    void handleToRadio(const char *buf, size_t len);
+
+    /**
+     * Get the next packet we want to send to the phone, or NULL if no such packet is available.
+     *
+     * We assume buf is at least FromRadio_size bytes long.
+     */
+    bool getFromRadio(char *buf);
+
+    /**
+     * Return true if we have data available to send to the phone
+     */
+    bool available();
+
+    //
+    // The following routines are only public for now - until the rev1 bluetooth API is removed
+    //
+
+    void handleSetOwner(const User &o);
+    void handleSetRadio(const RadioConfig &r);
+
+  protected:
+
+    /**
+     * Subclasses can use this as a hook to provide custom notifications for their transport (i.e. bluetooth notifies)
+     */
+    void onNowHasData(uint32_t fromRadioNum) {}
+
+  private:
+    /**
+     * The client wants to start a new set of config reads
+     */
+    void handleWantConfig(uint32_t nonce);
+
+    /**
+     * Handle a packet that the phone wants us to send.  It is our responsibility to free the packet to the pool
+     */
+    void handleToRadioPacket(MeshPacket *p);
+};