GPSMsg: made collection be a state machine (eavesdropping)
5438_gps: add SiLabs Si4463 test module to h/w defs (platform)
5438_gps: turn on FORCE_ATOMIC, TRACE_MICRO, add platform_panic
mm4, mm5t: add platform_panic
make v3: move exp5438, mm{3,4,5t} build files to new places.
mm5t: add Panic and Platform wiring
mm{3,4,5t}, exp5438_gps: rework platform/target for make v3