[voeutthc] Clock for simultaneous chess

A single clock for the simul giver.  This allows time to be strategically allocated between games.

Decrements faster depending on how many boards are your turn, e.g., 5 seconds per second if there are 5 boards that are your turn.

Figure out a UI that is not confusing.  A line graph with diagonal extrapolates showing the maximum rate the time might decrement?

What to do with time left over from finished games?  Probably nothing, though extrapolation needs to know those boards will never be your turn.

Not for simultaneous exhibition where you wait for the master to arrive at your board before making your move, but an idea where a round robin tournament is played simultaneously by all players, so needing O(n) clocks total instead of O(n^2).