Merge pull request #3 from dwtj/master

4-24
Updated the remaining handlers to utilize rx_frame(), implemented movement stoppers (cliff and bumper detection) TODO: implement detection of white things, and send appropriate message post-detection.
Merge branch 'master' of https://github.com/dwtj/mars-rover into dwtj-master

Conflicts:
	rover/src/lcd.c
	rover/src/servo.c
Made song test code in `main()` into its own mode to be selected.