Temp: Add marker relative release

Allowing adding marker relative to other marker

Needs validation on text input

3D measurements

Changes

• Markers now store their position in 3 dimensions, with z representing altitude (or inverse depth).
• Rulers now measure in 3 dimensions. Measurements can be started from a Marker, and it's possible to set the depth of the end point from a marker as well.
• Markers can now have a description of up to 500 characters.
• When starting the application, the last saved map will now loaded (if any).
• If any changes have been made, a "Save changes" prompt will appear upon exiting the application.

Add scale indicator

Changelog

0.2.0

• Added scale indicator
• Add/edit marker dialog now opens in the middle of the app window

Initial release

This is the initial release, stuff is working well enough to be of some use I think :)