need to add standard libs like EEPROM here

standard libraries like EEPROM are now in the 'hardware/avr' tree and need to be cloned in order to be available for the xmega.  otherwise, the include path won't be correctly assigned.

The best way to do that would be to just clone the source as a separate lib, and make sure they work on xmega.  This means maintaining them against the avr source changes, however.
