added smartport telemetry

Conflicts:

	src/main/telemetry/telemetry.h
added single wire half duplex UART

Conflicts:

	src/main/telemetry/telemetry.h
Updating telemetry documentation to cover SmartPort (S.Port).
Minor formatting fix.
Adding details of the new serial port scenario for SmartPort telemetry.
Adding a FIXME to the SmartPort code.
Allow smartport to be configured.  Fix shared port flag calculation.