0.5a release

I’m going to call this 0.5a.  Some testing and integration remains, but
it provides a good idea of what 0.5 is.
0.5a merge conflicts

Conflicts:
	otlib/crc16.c
	otlib/m2_dll_task.c
	otlib/m2_encode.c
	otlib/m2_transport.c
	otradio/spirit1/radio_SPIRIT1.c