Mission Command's AltType is not saved to .wp file

It seems that when the "Save WP File" button is pushed, it saves a .wp file but the command's individual altitude type is still being read from the upper level altitude type selector.

To recreate the problem do this:

- create a mission with 2 commands, leave the upper level altitude type to "Relative"
- set the 2nd command's altitude type to terrain
- press "Save WP File" button and then open the resulting file in a text editor
- the 3rd column for the 2nd command should be "10" but it will be "3"

Reproduce the issue in Mission Planner by creating two commands, setting the second command's altitude type to terrain while the upper selector remains Relative, and pressing the "Save WP File" button. Inspect the resulting .wp file in a text editor; done means the second command's third column is "10" rather than "3".

Written by the indexing model from the issue text.