Added in checks for being connected to a MAV before attempting edits of configuration in Battery Monitor Config

Implementation of Battery Monitor configuration, and addition of AP2ConfigWidget, which automatically handles UAS connections to allow for simpler configuration window code.

Additional functionality for Flight Mode config, including highlighting of current PWM value on channel 5

Some comment cleanup, and fix so when closing the main window, it also closes the item select window

Removed OpenGL dependency in HUD, merged in HUD from Soren Kuula and config changes from Michael Carpenter

Impl. Lorenz suggestions wrt one velocityChanged, altitudeChanged, speedChanged signal per reference frame. Impl. CDI on compass disk.

Change so MainWindow handles its own deletion, and deletion of other UI objects to allow for closing when the MainWindow is closed, regardless of if other windows are open.