Changed ATmega168 port to ATmega328 on Uno R3 with DFR0259 RS485 shield (#784)

* Changed ATmega168 example for ATmega328 on Arduino Uno R3 with DFR0259 RS485 shield. Added ADC interface from BDK port and mapped to some AV objects. Removed MS/TP MAC address DIP switch GPIO and moved MS/TP configuration to AV objects. Added AV units property. Added some Uno R3 Digital Inputs and outputs mapped to some BV. Added AVR EEPROM from BDK port and mapped some non-volatile data including MAC address and max manager and baud rate, device ID and names and description and location.

src/bacnet/bacapp.c

@@ -1944,6 +1944,7 @@ static int bacapp_snprintf_property_identifier(
     return ret_val;
 }
 
+#if defined(BACAPP_NULL)
 /**
  * @brief Print an null value to a string for EPICS
  * @param str - destination string, or NULL for length only
@@ -1954,6 +1955,7 @@ static int bacapp_snprintf_null(char *str, size_t str_len)
 {
     return bacapp_snprintf(str, str_len, "Null");
 }
+#endif
 
 #if defined(BACAPP_BOOLEAN)
 /**