Refactor/mstp zero config state machine (#676)

* Changed MS/TP master node self destination checks to be located in receive FSM

* Changed MSTP zero configuration: modified comments for state transition names; modified next station increment; refactored the UUID rand() to not be required by common zero config implementation; added more unit tests.

* Added another context to MS/TP user data to allow additional user data

ports/xplained/rs485.h

@@ -25,6 +25,9 @@ void rs485_bytes_send(uint8_t *buffer, uint16_t nbytes);
 uint32_t rs485_baud_rate(void);
 bool rs485_baud_rate_set(uint32_t baud);
 
+bool rs485_kbaud_rate_set(uint8_t baud_k);
+uint8_t rs485_kbaud_rate(void);
+
 uint32_t rs485_silence_milliseconds(void);
 void rs485_silence_reset(void);