Changed XPLAINBridge project to be both a USB to USART bridge and a PDI programmer, based on the state of a mode select pin.

Fix project text files to refer to "project" instead of "demo".

Started implementing the low level PDI protocol in the AVRISP project, for XMEGA device programming.

Add new more reliable software UART for the XPLAINBridge project by David Prentice and Peter Danneger.

Removed John Steggall's software UART code from the XPLAIN Bridge project due to reliability issues.

Enable pullup on the PD5 pin of the AVR in the XPLAINBridge project - this is connected to the XMEGA's /RESET line, need to enable pullup to prevent spurrious resets.

Added new RNDISHost Host LowLevel demo. Fixed misnamed Pipe_SetPipeToken() macro for setting a pipe's direction. Fixed CDCHost failing on devices with bidirectional endpoints.