Arasan 15.3

[jdart]

Arasan 15.3 is available from http://www.arasanchess.org.

Changes in this release:

1) Fix a bug in king cover calculation.
2) Modify root LMR logic.
3) Reduce memory usage for "makebook" utility by shrinking/packing structures.
4) Fix "makebook" so it works on Linux.
5) Improve makebook speed by optimizing Board::reset.
6) Some tweaks to trade down scoring, especially to discourage trading down from a possibly winnable to a drawish endgame.
7) Change hashtable replacement policy so exact hash code matches always replace existing entries.
8) Main search probes q-search cache for a pv move if the main hash table does not provide one.
9) Improved ordering of evasion moves.
10) Add extra time to search if resolving a fail-high at the root.
11) Thread limit raised to 64.
12) Thread split depth is dynamic based on number of threads.
13) Some code portability fixes, in particular fixing big-endian support.

This version scores about 25 ELO higher than 15.2 in my testing. YMMV.

--Jon