Rename software USART driver globals to make the code more in line with the rest of the XPLAINBridge project.

Make software USART used in the XPLAINBridge project directly check and store into the ring buffers, rather than polling from the main program loop to avoid added latency.

Create a new LightweightRingBuffer.h header file for the XPLAIN project to abstract out the new ring buffer without a performance penalty.

The RingBuff library code has been replaced in the XPLAINBridge project with an ultra lightweight buffer to help  improve the reliability of the bridge.

Add svn:eol-style property to source files, so that the line endings are correctly converted to the target system's native end of line style.

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.