Made all of the indentation consistent.  Removed dead
code.  Use "//" comments exclusively.  Removed comments
that were just occupying space. etc.
Merged the RasPi raspi.c file into motor3.c.  (Actually
it is the other way around.)  This is an ugly intermediate
step in the process.
Converted motor3 and raspi to use common/common.h.
Moved shared code between motor3 and raspi over to common/common.c
with common.h as the header file.
Merge commit '23a60bd1cf646ae99acc7d842b6ca25107df5d6c'

Conflicts:
	common/common.h
	common/robus.mk
	motor3/rev_d/motor3.c
	raspi/rev_b/raspi.c

Merge code that uses common.c and common.h.  Really this was
accidentally done on a different branch; hence the merge.
Broke common.h into a bunch of specialized .h files.
Migraded Discovery structure back to raspi.c.