Fix 4830 wige jumps to bottom of water hex

[Sleet01]

This should fix a few problems with WiGE jump jets in MM:

1. WiGE jumps to one elevation above the terrain beneath the water level,
2. MM Prompts for a PSR when a WiGE jumps into a water hex, but does not prompt Hovers or WiGEs entering normally.
3. WiGE not getting set to an elevation that's high enough to be considered "flying",
4. MM prompting for automatic landing if the WiGE doesn't jump 5+ hexes (a WiGE may not land in a turn it jumps)

Vehicle jump damage checks appear to otherwise be correct.

Ran MM verification tests and tested with both player- and Princess-controlled vehicles.

Close #4830