latest moves highlighting & history browsing

[zpmorgan]

only the most recent move is highlighted It would be nice if it showed more info, especially with random turns & 3color.

It should show you moves since your last move, and let you travel through time with 'rewind' & 'forward' buttons, as well as use the moves drop-down list.

If client is only given a list of position deltas, redrawing is limited & bandwidth saved.