Added THREECHAN protocol for Three channel weather station support.

Added Three channel weather station protocol. 

Protocol.c remaining inserts:

Insert line 123:
<code>
#ifdef PROTOCOL_THREECHAN
	#include "../protocols/threechan.h"
#endif 
</code>

Insert Line 221:
<code>
#ifdef PROTOCOL_THREECHAN
	threechanInit();
#endif 
</code>