Add of SONOFF RFR3 environment

Relay ok
Button press ok
RF reception 433toMQTT ok
To have the RF reception you need to connect D0 of SYN470 to GPIO4 of ESP8285. Instruction to follow. Do not do that if you are not confortable with soldering and don't have an electrical background.

main/config_ONOFF.h

@@ -35,12 +35,14 @@ extern void MQTTtoONOFF(char * topicOri, JsonObject& RFdata);
 #define subjectGTWONOFFtoMQTT  Base_Topic Gateway_Name "/ONOFFtoMQTT"
 
 /*-------------------PIN DEFINITIONS----------------------*/
-#ifdef ESP8266
-    #define ACTUATOR_ONOFF_PIN 15 //12 for sonoff basic relay
-#elif ESP32
-    #define ACTUATOR_ONOFF_PIN 15 
-#else
-    #define ACTUATOR_ONOFF_PIN 13
+#ifndef ACTUATOR_ONOFF_PIN
+    #ifdef ESP8266
+            #define ACTUATOR_ONOFF_PIN 15 //12 for sonoff basic relay
+    #elif ESP32
+        #define ACTUATOR_ONOFF_PIN 15 
+    #else
+        #define ACTUATOR_ONOFF_PIN 13
+    #endif
 #endif
 
 #endif