Record the past

[IRHM]

For now we can have a simple dropdown for this setting, defaulting to off and changeable to different increments (2, 3, 5, 8, 10, 15, 20, 30 min).

When it's on, I guess we have to record to a temporary file constantly, pruning it so we don't have a massive temporary video file. Then when the record past x min keybind is pressed, we will copy that temp file (shorten if necessary) into a new recording.