* new helper for ESP32: SerialBLEInterface

* Some refactoring in BaseChatMesh and Terminal Chat
* new companion_radio example

src/helpers/BaseSerialInterface.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <Arduino.h>
+
+#define MAX_FRAME_SIZE  160
+
+class BaseSerialInterface {
+protected:
+  BaseSerialInterface() { }
+
+public:
+  virtual void enable() = 0;
+  virtual void disable() = 0;
+  virtual bool isEnabled() const = 0;
+
+  virtual bool isConnected() const = 0;
+
+  virtual bool isWriteBusy() const = 0;
+  virtual size_t writeFrame(const uint8_t src[], size_t len) = 0;
+  virtual size_t checkRecvFrame(uint8_t dest[]) = 0;
+};