Plus low battery announce changes

Plus fixed a bunch of bugs

Instead of hardcoded "QGroundContorl" strings

Plus remove unused code

- Look backwards from insert point
- Only pull altitude from _WAYPOINT items
- Only set altitude on _WAYPOINT items

* Holds all the settings for the app
* Allows core plugin to override default values

Also added ui support for multiple complex item types

- Shot Interval in Survey
- Much change to time/distance calc