Experimental new multichannel recorder interface with FFMPEG encoder implementation.

Signed-off-by: Steven Lovegrove <stevenlovegrove@gmail.com>
Move static defines into cpp file.
Added experimental support for recording views. Currently no stop mechanism and shows flipped.

Signed-off-by: Steven Lovegrove <stevenlovegrove@gmail.com>
Screen recording working pretty smoothly. Recording API still beta.

Signed-off-by: Steven Lovegrove <stevenlovegrove@gmail.com>
Recorder make filename unique option. Some bug fixes. Handle time base better.

Signed-off-by: Steven Lovegrove <stevenlovegrove@gmail.com>
When attaching pangolin vars to cvars, replace spaces in name so that they can be saved correctly.
Register some pangolin cvar util functions.
Heed BUILD_PANGOLIN_VIDEO define for window video recording.
Add glDrawCirclePerimeter method and fix round bug with abs for LayoutEqual.