#12 Timing controls sometimes causes blunder

[Mike Maxim]

The timing code is bad enough that sometimes the
engine will abort thinking with a move searched to only 6
or so play with still plenty of time. It returned a PV in a
game against BigLion that resulted in checkmate for
Simontacchi's side. With 6 seconds it could have
avoided the blunder and won the game.

[Mike Maxim]

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I sort of alleviated this problem by having the in alpha-beta
routine check if the full interval has passed, as opposed to
some fraction of that interval. However I still need to think
about better time management.

[Mike Maxim]

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There should be a mechanism that extends the time period if
the PV has changed drasticaly (80 centipawns?) since the
last iteration.