Renamed the Serial byte send/receive functions to remain consistent with the CDC driver's byte functions.
Altered the serial byte receive function to make it non-blocking.
Add a new RFCOMM_ChannelSignalsReceived() Bluetooth stack callback from the RFCOMM layer for when the remote device sends new terminal control signals.
Fix RFCOMM_SendData() not aborting correctly when the requested RFCOMM channel is not found.
Add a new RFCOMM_SendChannelSignals() function to transmit a change in V24 terminal handshake lines to the receiving device.
Prevent SABM packets sent to the control DLCI in the RFCOMM layer from creating a new channel entry, as the control DLCI does not have connection data associated with it.
Fix up MSC control packet handling so that received responses can be acknowledged correctly, so that the RFCOMM layer can record when the receiving device has ACKed a sent change in V24 terminal handshake lines.