Turn the news ticker or clock on or off, rename, reorder or retime a slideshow

Changes a slideshow; send only what should change. Turn the news ticker on or off and pick its sources (ticker), show, hide, move or recolour the on-screen clock (clock), set how long each slide shows (defaultDurationSeconds), share it (shared), rename it (title), change the screen size (resolution), reorder all slides (slideOrder), or switch playbackMode (Auto, VideoStream, Html, or inherit to clear the override; leave it alone unless the person asks, new workspaces choose automatically). Only changes that affect the rendered video queue a re-render; ticker, clock and title changes reach screens on their next poll.