Optimized transmitter calibration wizard metadata rates.

Also solved bug by which update rates were incorrectly reset during
the wizard. In this case, there was a metadata reset followed immediately
by a set. This reset/set operation occurs too quickly and the telemetry
system only sends the first operation to the board. The result was that the
final steps of the wizard were very slow.
Optimized telemetry rates for calibration class.
Changed ReceiverActivity to throttled. This is justified because this UAVO
is only used by GCS in order to identify the transmitter channels
Improved comments about transmitter calibration routine. Fixed missing
UAVOs.
Changes requested in review.