* Command ack timeout back on normal/high latency link
* Correctly update ack timeout and high latency bit at correct times

When downloading mission items from the autopilot we need to retry more
agressively, so use a shorter timeout. If we don't do this, we might not
re-request a mission item in time and the autopilot has already given up
the overall mission transfer.

This fixes the case where a mission request from QGC to autopilot or a
mission item from autopilot to QGC gets lost on the link and needs to be
requested again.

* Flight modes still not implemented. Waiting on message change.
* Also includes various cauterization of UI things which should not be
available on high latency link.

By adding a member variable for the total mission item count, we can
actually correctly estimate the progress.

It was broken when temperature translation was added in babbfbd1
The system wasn't quite setup to handle anything other than speed and distance. Changed so any arbitrary unit type can be converted to another.

It was broken when temperature translation was added in babbfbd1
The system wasn't quite setup to handle anything other than speed and distance. Changed so any arbitrary unit type can be converted to another.

Float comparison to flakey cross-platform

Move  MAV_PARAM_TYPE to  MAV_PARAM_EXT_TYPE as we're now using the proper MAVLink version.