Add --test-high-dpi command line option

This allows for testing issues found on high dpi screen without needing
a high dpi screen. it does this by doubling the font sizes.

Add Delete, Move Up, Move Down

Plus more overall ui work

Stop using fixed pixel count spacing

More MissionEditor work

- New MissionManager
- Plumb MissionManager through MissionEditor
- Mission Editor supports get/set

Mission work

Fixing Android screen orientation.

It now uses the sensor to maintain proper landscape mode.

Update NSIS script to include ANGLE dlls for windows, add NSIS script…

Enable Android Video Streaming

Map menu fixes

- Only show video option if supported
- Persist settings
- Show/Hide/Add items correctly

While at it, fixed an issue with builds that have video streaming disabled.

Add switch for using old/new mission editor

More mission editing work

Add video background support

Mission editor (WIP)

- Restructured a number of MissionItem properties as well

appveyor support (windows ci)

fix linux unittests failure