Merge pull request #1 from dwtj/master

Merge David's Ping
Refactored errything. Moved everyting outside of Control to respective subsystem files, deleted COMM.H. PING works.
Outlined ISRs, no longer compiles probably. Did some refactoring, probably. Echo probably works.
Merge https://github.com/asr1/mars-rover into asr1-master
Re-added `aux.py`. It keeps getting deleted for some reason!