The GPS/RNAV system can now fly holds, both left and right-handed.
The correct entry is selected, and hold count can be selected.
Also there's lots of lovely test cases.
Revert this change - I will re-add the unit-tests again, but we need
a different approach for 8.3 stations, than what I did here.
This reverts commit 91cc83abb5.
In 8.3 mode, ensure that 25 and 75Khz channels can be tuned using the
abbreviated syntax (eg 118.02 for 118.025).
As part of this, add test coverage of the CommRadio for basic and 8.3-
mode operation.
