Sends ND message to remote radios and catches replies.
Local coordinator also replies, need to add something to "filter" that response
out and not add it to the list of nodes with sensors.
Removed loop period delay (seconds) - current delay is 100 mSec. Longer delays
appeared to cause packet drop.
Cleanups and reorganizing state stuff.
Compiles but untested.
Working ND code. Only does one discovery at startup, meaning
any nodes added after startup will not be discovered.