Release 283

A very minor release to fix an edge case with the V3.3 AVR firmware.

When a high volume of URF, Universal RF, commands are being sent to the AVR due to timing critical code no buffering of incoming serial data was happening as interrupts where disabled.  If a command is sent to the AVR whilst is still processing the URF sequence this data (command) would be lost.

Resolved by implemented XON/XOFF Software flow control between the AVR and the HAH xap-livebox process.

When the AVR is attending to a URF command it will inform the HAH to pause sending serial data (XOFF) and it will re-enabled (XON) once the RF command sequence has been sent.  This ensures that no data gets lost.

This is an unusual edge case that most folks would not run into, still its worth fixing to improve the overall stability.

You MUST update both the HAH to build 283 and the AVR to v3.4 to fix this problem.