Re-add in flip, flip-ee, dfu and dfu-ee targets to project makefiles (thanks to Opendous Inc.)
Fix allowable F_CPU values comment in project makefiles.
Added new Endpoint_SetEndpointDirection() macro to set the current endpoint direction for bidirectional endpoints.
Renamed internal USB_INT_ENDPOINT_SETUP macro to USB_INT_RXSTPI to fit in with the rest of the interrupt vector macros.