Add Diag::SNIFFER so config verbosity of sniffer output

CommandStation-EX.ino

@@ -168,6 +168,7 @@ void loop()
     DCCPacket p = dccSniffer->fetchPacket();
     if (p.len() != 0) {
       if (DCCDecoder::parse(p)) {
+	if (Diag::SNIFFER)
 	  p.print();
       }
     }

DCCDecoder.cpp

@@ -42,8 +42,10 @@ bool DCCDecoder::parse(DCCPacket &p) {
   for (byte n = 0; n < p.len(); n++)
     checksum ^= d[n];
   if (checksum) {  // Result should be zero, if not it's an error!
+    if (Diag::SNIFFER) {
       DIAG(F("Checksum error:"));
       p.print();
+    }
     return false;
   }
 

DCCEXParser.cpp

@@ -1277,6 +1277,10 @@ bool DCCEXParser::parseD(Print *stream, int16_t params, int16_t p[])
         Diag::LCN = onOff;
         return true;
 
+    case "SNIFFER"_hk: // <D SNIFFER ON/OFF>
+        Diag::SNIFFER = onOff;
+        return true;
+
     case "WEBSOCKET"_hk: // <D WEBSOCKET ON/OFF>
         Diag::WEBSOCKET = onOff;
         return true;

StringFormatter.cpp

@@ -29,6 +29,7 @@ bool Diag::ETHERNET=false;
 bool Diag::LCN=false;
 bool Diag::RAILCOM=false;
 bool Diag::WEBSOCKET=false; 
+bool Diag::SNIFFER=false;
 
 
  

StringFormatter.h

@@ -32,7 +32,7 @@ class Diag {
   static bool LCN;
   static bool RAILCOM;
   static bool WEBSOCKET;
-  
+  static bool SNIFFER;
 };
 
 class StringFormatter