Arasan 15.2

[jdart]

Arasan 15.2 is available from http://www.arasanchess.org. This is basically the version that played in the recent CCT tournament.

Changes in Arasan 15.2:

1) Some speed improvements especially when multithreaded.
2) Code cleanup and bug fixes related to draw handling (could lose on
time in server games, in rare cases, due to problems in this area).
3) Some more code conversion to C++ style intead of C. Use STL pair template.
4) Minimum search time changed to 10ms to better support very fast test
games.
5) Bug fix in code for checks in qsearch: ensure checking moves do not
place own king in check.
6) Some weights changed in scoring module based on CLOP.
7) Simplified razoring code.
8) Qsearch forward pruning changes. We use only pre-selection of captures now, not traditional forward pruning. Margins for this adjusted.
9) Linux-specific bug fix for occasional crashes when >2 threads in use.
10) Fix in aspiration window code for rare overflow condition when
failing low with a mate score.
11) Fix bug setting hash sizes > 2GB through Winboard/UCI.
12) Somewhat more general Rook pawn vs wrong color Bishop draw detection.

This version is measurably stronger than 15.1 but nothing dramatic: I think around 20 ELO.

--Jon