scrolling marquee in ticker field

Closes #801 though we may want another ticket for figuring out how to get RSS feeds into the ticker area.

To test, add some ticker content, and then set up two field config's on your ticker field-- one for shuffle:BaseShuffle (wouldn't want multiple copies [via weighting and the WeightedShuffler) and one for marquee:checked.

When this is setup like the above, the frontend controller sends up to 20 pieces of ticker content to the screen which then puts it together for marquee display, sets the timeout for around two complete iterations, sets the font height, and starts displaying it.