Support for Vehicle and Firmware classes

Initial support for global plan-wide altitude mode setting

Rework handling of fw/vehicle type with respect to conflicts with actual vehicle types.

Use consistent "Launch" naming

RTL is no longer part of Mission Settings

SectionHeader no longer set width automatically

Switch to clearer property usage

Waypoints only mode tweaks

Show camera section in waypoints only mode

Hide flight speed and camera section for ArduPilot. This is because it doesn't allow mission items to be before the TAKEOFF command.