Minor user interface issues

#### Issue details
1. simulation starting heading range is 0..100. Definitely, it should be 0..360 or -360..360
2. HUD altitude uses distance measuring units
3. Vertical speed is always in m/s, but if feet altitude units configured it's better to use fps
4. On Flight Data view status bar shows altitude value in meters and feet correctly, but unit mark doesn't change from "m" to "f" when in feet.

#### Version
MP 1.3.55

#### Platform
[ x ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

Reproduce the four reported behaviors in Mission Planner, including the simulation heading range, HUD altitude and vertical-speed units, and the Flight Data status-bar label with feet configured. Trace the corresponding desktop UI displays and unit-setting handling; the work is done when each value, range, and unit mark follows the configured measurement system.

Written by the indexing model from the issue text.