Settings fixes

Moving more settings to new SettingGroup mechanism

Plan: Change semantics for pulling altitude from mission items for new items

Add new SettingsGroup support

ArduPilot: Beta firmware drops using new format

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

Allow plugins to change/replace toolbar indicators.

Fixed a small binding loop in RallyPointEditorHeader.qml

Add bool support to FactSystem

Update mavlink v2

Convert bool settings to SettingsFact

FactSystem: String support

Complex item visual dynamically added to map

Addition of "Abort" button

Fly view: Use new ToolStrip

Add/use new SettingsManager implementation

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