Show home position on flight map

Icon Tweaks

Add another Firmware detect fallback

Tweaking MapType and MapCenter icons
Added Zoom Plus/Minus icons to be used for maps
Added PiP icon for the upcoming Picture-in-Picture functionality

More Drop Button, Mission Editor, Map work

Add new DropButton control - WIP

Icons for Map Display

[WIP] appveyor windows builds

No widgets in mobile builds

Fixed QtLocation Caching

Home position manager

Updated Google Maps API Version
Updated User Agent used for map tile requests

Also:
- Remove unused code

Use import QGroundControl 1.0 to get to it

Take MissionManager off separate thread

travis-ci android add gstreamer

Change arm/disarm mavlink message usage

Support load/save

Fix APM adjustMavlinkMessage

Also understand the concept of missions which cannot be edited

This was done to support both PX4 and APM flight stack with same code