archiving: let use custom timestamp.
use the same timestamp for all recordings.
archiving: cleanup, fix initialization
archiving: back to old behaviour, logging.

Setting all the pipeline to NULL before recording is not optimal but
works for now.
inputs: move initialization and geometry to base class.

Also:
    Adds push and pop geometry functions.
    C920: set geometry to system wide size by default.
make VideoMixerTransition aware of push_ and pop_geometry()
use fast transition by default when starting PiP.
archiving: adds missing method to base class.
BaseH264Output: send a keyframe+burst on new client.
inputs: minor cleanup.
C920: restore geometry on state changes.

    if another input was added in between we may have negotiated a
different size.
make fakesink sync on the clock.
pruning old code
adds video inserts and link them to the correct audio mixer.
adds missing .ui file
adds basic widget to control recording.
adds tabbed interface. has debug buttons, remember to take them out.
main: use RecordWidget and new ui, reorder code
RecordWidget: create folder if it doesn't exist