Ultrasonic distance ranger

This is a work in progress; I'm posting it mostly to share the new parts. IT HAS NOT BEEN TESTED.

The new parts are a Devantech SRF08 sonar range-finder (several other Devantech sonars are very similar) and an AT25160 serial EEPROM.

I'm just now starting to learn Arduino, and I've gotten distracted by a few other projects, so this make take a while.