Arasan 12.0 released

[jdart]

Arasan 12.0 is available from http://www.arasanchess.org. I have made some additional fixes and improvements compared to the version that played in the recent WCRCC tourney.

Changes in Arasan 12.0 (Aug. 2010):
1) Eval code is changed to split eval terms more explicitly into opening, middlegame and endgame terms and these are merged via a weighting function based on material.
2) Some eval changes to king safety, bishop pair, etc.
3) King safety cache was also used for opponent pawn proximity - but the hashing didn't account for opponent pawns. This is fixed by not storing proximity in the cache.
4) Material score adjustment added for Q vs R + Pawns, and R vs pawns.
5) Some new "trade down" bonus code is present to encourage exchanging when ahead - there was some code for this earlier but less correct.
6) Fix to futility pruning margin calculation.
7) Fixed a Winboard/xboard driver bug where some "ping" commands from ICC were being ignored.
8) Fix a rarely occurring bug in qsearch: generating a check that involves moving a pinned piece.
9) Fix bug in razoring code that could cause array overflow at very large search depths (as in endgame).
10) Fix display in GUI game list dialog & main window to include year of game

I have also updated the Arasan test suite, which now has 237 positions.