Signing infrastructure refactored

Signing logic has now been centralized to MySigning.cpp in order to simplify
maintenance and debugging.
Debug prints have been extended and "demoted" to verbose level.
To get signing related debug info, MY_DEBUG_VERBOSE will need to be defined.
This fixes #278

libraries/MySensors/core/MyMessage.h

@@ -163,9 +163,9 @@ typedef enum {
 	I_INCLUSION_MODE, I_CONFIG, I_FIND_PARENT, I_FIND_PARENT_RESPONSE,
 	I_LOG_MESSAGE, I_CHILDREN, I_SKETCH_NAME, I_SKETCH_VERSION,
 	I_REBOOT, I_GATEWAY_READY,
-	I_REQUEST_SIGNING,    /*!< Indicates sender require signed messages (bool param) */
-	I_GET_NONCE,          /*!< Request for a nonce */
-	I_GET_NONCE_RESPONSE, /*!< Payload is nonce data */
+	I_REQUEST_SIGNING, /*!< Indicates sender require signed messages (bool param) */
+	I_NONCE_REQUEST,   /*!< Request for a nonce */
+	I_NONCE_RESPONSE,  /*!< Payload is nonce data */
 	I_HEARTBEAT, I_PRESENTATION, I_DISCOVER, I_DISCOVER_RESPONSE, I_HEARTBEAT_RESPONSE
 } mysensor_internal;