Pre-Wednesday Work Session

Get to work!
Wednesday Afternoon

Main function and TWI comms working OK. Note usi_twi_slave never returns
and the idle function can't contain delays - ie, the usi_twi_slave
function is constantly polling, which is a bit of a pain.
TWI/I2C OK

Communications now spot-on, confirmed primary/secondary command
behaviour
Arduino Command Sender

Finished Arduino command sender for easy debugging.