Some code clean, and buffer overflow prevention (2) (#126)

* Remove trailing whitespaces

* RFM69toMQTT: Add the emitting nodeID to the topic, +

 - And remove radio.receiveDone() that is unecessary.
 - Send the ACK before the publish to MQTT, to be faster
 - Prevent buffer overflow, Terminate the data with a "\0"
   - Fix issue with the sender doesn't end its string with "\0"
     and rely only on DATALEN.

* Change topic subjectGTWRFM69toMQTT to be distinct from the commands

 + comments

* MQTTtoRFM69: deduplicate the code

 - Check once and only once if the topic is good.
 - Have or not RCV_ marked doesn't change the structure, as
   valueRCV is correctly set anyway
 + realign

* MQTTtoRFM69: Limit the size of the data

 - Cut the packet to the limit of what can transmit RFM69
   - and terminate the string

* RFM69toMQTT: ACK MQTT message on subjectGTWRFM69toMQTT now contains the nodeID

* RFM69: Publish to MQTT the RSSI on transmit and ACK

config_RFM69.h

@@ -1,15 +1,15 @@
-/*  
-  OpenMQTTGateway  - ESP8266 or Arduino program for home automation 
+/*
+  OpenMQTTGateway  - ESP8266 or Arduino program for home automation
 
-   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal  and a MQTT broker 
+   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal  and a MQTT broker
    Send and receiving command by MQTT
- 
+
    This files enables to set your parameter for the radiofrequency gateways (ZgatewayRF and ZgatewayRF2) with RCswitch and newremoteswitch library
-  
+
     Copyright: (c)Florian ROBERT
-  
+
     This file is part of OpenMQTTGateway.
-    
+
     OpenMQTTGateway is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
@@ -25,12 +25,18 @@
 */
 
 /*----------------------RFM69 topics & parameters -------------------------*/
+// Topic where the message from RFM69 will be published by the gateway,
+// appended with the nodeID of the sender
 #define subjectRFM69toMQTT "home/RFM69toMQTT"
-#define subjectRFM69toMQTTrssi "home/RFM69toMQTT/rssi"
+// Upon reception of a packed, the RSSI of that packet will be publish to this topic,
+// appended with the nodeID of the sender
+#define subjectRFM69toMQTTrssi "home/RFM69toMQTT/rssi"  // Comment this if you don't want the RSSI to be published.
 #define subjectRFM69toMQTTsender "home/RFM69toMQTT/sender"
+// Topic subscribed by the gateway. Messages received will be sent to RFM69
 #define subjectMQTTtoRFM69 "home/commands/MQTTtoRFM69"
 #define RFM69receiverKey "RCV_" // receiver id will be defined if a subject contains RFM69receiverKey followed by a value of 3 digits
-#define subjectGTWRFM69toMQTT "home/RFM69toMQTT"
+// On reception of an ack from RFM69, the message that has been sent is published here
+#define subjectGTWRFM69toMQTT "home/RFM69toMQTT/acked"
 #define defaultRFM69ReceiverId 99
 
 // Default values
@@ -48,9 +54,9 @@ const char PROGMEM RFM69AP_NAME[] = "RFM69-AP";
 #define IS_RFM69HCW    true // set to 'true' if you are using an RFM69HCW module
 #define POWER_LEVEL    31
 
-/*-------------------PIN DEFINITIONS----------------------*/ 
+/*-------------------PIN DEFINITIONS----------------------*/
 #ifdef ESP8266
-  #define RFM69_CS      D1  
+  #define RFM69_CS      D1
   #define RFM69_IRQ     D8   // GPIO15/D8
   #define RFM69_IRQN    digitalPinToInterrupt(RFM69_IRQ)
   #define RFM69_RST     D4   // GPIO02/D4
@@ -61,5 +67,3 @@ const char PROGMEM RFM69AP_NAME[] = "RFM69-AP";
   #define RFM69_IRQN    digitalPinToInterrupt(RFM69_IRQ)
   #define RFM69_RST     9
 #endif
-
-