Major update to simplify and document the custom build example

Use parsebin for automatic stream demuxing and parsing; Automatically insert rtpjitterbuffer for RTP streams to avoid video stuttering

qobject_cast is times faster then dynamic_cast for objects
that inherit QObject. also, use auto keyword to not repeat
the class name

qobject_cast is times faster then dynamic_cast for objects that
inherit QObject. Also, use auto keyword to not duplicate the
name of the Class

Fix gimbal indicator so that angle values match the markers
Select thermal mode on thermal menu selection

Custom vehicle selector now affected by theme change. Cosnistent with other actrive elements

Drawer now affected by theme, consistent with the rest of the active elements.

TODO: Add hover for desktop

Ligther Button, Primary and Hover + New alert color

Added gimbal pitch SVGs for indoors and outdoors theme

fix to even out the toggle buttons

Custon On / Off  switch updated to show label when off. Now works more like a toggle

Custom Example: Fix gimbal state getting out of the limits. Fix palette button not working if not in thermal mode. Increase zoom buttons