Structure scan fixes (V2)

Fix capatilization

Fix layer heights

More work on Structure Scan rewrite

Bug fixes for Structure Scan. Also includes support for Entrance/Exit Alt.

Check box check mark using vector image

Stable merge

PX4: Warn if HITL is enabled on vehicle

Move position of HITL to bottom. Handle no SYS_HITL param.

Warn if SYS_HITL is set

Fix debug output

Use correct number of available channels

Appveyor: Switch to Stable 3.5

USe correct number of available channels

Bring fixes from Stable_V3.5 -> master

Use any libicu version

Fix typo in CodingStyle.qml

Structure Scan: Add support for Start From Top/Bottom, plus more helpful stats

Add support for Start From Top/Bottom, plus more helpful stats

PR android joystick improvement v2

When starting up, if you start the GS before connecting the bluetooth joystick the QGC needs to be closed and restarted to get it to recognize the joystick

Fix crash bug that could occur when reconnecting a camera.

Make Apple happy

PR Taisync support for Android