convert to using stdio to line buffer usb output... This reduces
usb traffic like when doing hexdump...

The delay works, but could be a problem on slower systems...  It's
been reported, so hopefully a fix will happen..

This is better than using RAM, as it keeps the state between power
cycles...

The old method would introduce a race condition where the buffer
could be overwritten before the data was consumed.  For slow, single
character typing this was fine, but w/ packets being generated by
a computer, this would cause corruption of the incoming data..

a lot more will need to be added as we go on..

This was pulled from heltec's PingPong example, but all licenses
are free..  Also, the files were cleaned up, that is CRs removed,
and trailing white space removed from lines...