search path in platform updated to include cc2420csma updates
committed to shimmer2r last year that include the cc2420rxstate
interface, allowing apps to control cca and the rx strobe (sometimes
these get in the way in dense, tightly controlled traffic).

moteplatformc was updated to set the led pin, which has been up to
random state all of this time.
solely in order to silence an annoying compiler complaint about
uninitialized variables, the id array is now set to 0 before filling
it with the read call.