Introduce MY_DEBUG_VERBOSE to reduce binary size

Define MY_DEBUG_VERBOSE to have verbose debugging output (dumping NRF24
registers on startup).
Fixed warnings.

libraries/MySensors/drivers/RF24/RF24.h

@@ -210,9 +210,9 @@ public:
   /**@{*/
 
   /**
-   * Print a giant block of debugging information to stdout
+   * Print a giant block of debugging information to serial
    *
-   * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
+   * @warning Does nothing if MY_DEBUG_VERBOSE is not defined
    */
   void printDetails(void);
 
@@ -922,60 +922,60 @@ private:
    * @return Current value of status register
    */
   uint8_t get_status(void);
-
-#ifdef DEBUG
+ 
   /**
-   * Decode and print the given status to stdout
+   * Print the current feature register value to serial
+   *
+   * @warning Does nothing if MY_DEBUG is not defined
+   */
+  void print_feature(void);
+ 
+  /**
+   * Decode and print the given status to serial
+   *
+   * @warning Does nothing if MY_DEBUG_VERBOSE is not defined
    *
    * @param status Status value to print
-   *
-   * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
    */
-  void print_status(uint8_t status);
+  void print_status(uint8_t status) const;
 
   /**
-   * Decode and print the given 'observe_tx' value to stdout
+   * Decode and print the given 'observe_tx' value to serial
+   *
+   * @warning Does nothing if MY_DEBUG_VERBOSE is not defined
    *
    * @param value The observe_tx value to print
-   *
-   * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
    */
-  void print_observe_tx(uint8_t value);
+  void print_observe_tx(uint8_t value) const;
 
   /**
-   * Print the value of an 8-bit register to stdout
+   * Print the value of an 8-bit register to serial
    *
    * Optionally it can print some quantity of successive
    * registers on the same line.  This is useful for printing a group
    * of related registers on one line.
    *
+   * @warning Does nothing if MY_DEBUG_VERBOSE is not defined
+   *
    * @param reg Which register. Use constants from nRF24L01.h
    * @param qty How many successive registers to print
    */
   void print_byte_register(uint8_t reg, uint8_t qty = 1);
 
   /**
-   * Print the value of a 40-bit address register to stdout
+   * Print the value of a 40-bit address register to serial
    *
    * Optionally it can print some quantity of successive
    * registers on the same line.  This is useful for printing a group
    * of related registers on one line.
    *
+   * @warning Does nothing if MY_DEBUG_VERBOSE is not defined
+   *
    * @param reg Which register. Use constants from nRF24L01.h
    * @param qty How many successive registers to print
    */
   void print_address_register(uint8_t reg, uint8_t qty = 1);
 
-  /**
-   * Print a value in hex to serial output.
-   *
-   * For values < 16 a leading 0 will be printed.
-   *
-   * @param v  Value to print in hex.
-   */
-  void print_hex( uint8_t v, const bool prefix0x = false );
-  
-#endif
   /**
    * Turn on or off the special features of the chip
    *