Fixes #2595 - Cli added

Based on projectkk2glider work, with a lot of bugs I am sure. Still not
tested, this is why I preferred working on my own branch. I push it now
so that Jenkins do the first tests and you can review if I am on the
right track. 

I am really wondering if a merge with the Lua api would be possible /
nice, what do you think?

radio/src/opentx.cpp

@@ -2456,7 +2456,7 @@ void opentxInit(OPENTX_INIT_ARGS)
   backlightOn();
 
 #if defined(PCBTARANIS)
-  uart3Init(g_eeGeneral.uart3Mode, MODEL_TELEMETRY_PROTOCOL());
+  serial2Init(g_eeGeneral.serial2Mode, MODEL_TELEMETRY_PROTOCOL());
 #endif
 
 #if defined(PCBSKY9X) && !defined(SIMU)