Smart RTL support

Support STATUSTEXT_LONG

Remove the concept of reserved buttons for manual control

Add support for Orbit flight mode

Turn Orbit on

FirmwarePlugin: Issue a warning upon connecting if the firmware in use is not using a stable release

Turn off Orbit

Fix Change Command parameter default setting

Buggy and no longer needed

Remove/comment off debug output pollution

PX4 Firmware plugin: First try to switch flight mode, then arm if successful - which is a lot safer than arming and then seeing if we can switch modes.

Just use settings defaults

Fixed found bugs

Plus low battery announce changes