Arasan 16.2

[jdart]

Arasan 16.2 is available from http://www.arasanchess.org.

Changes in Arasan 16.2:
1) Fix adjacent passed pawn code so bonus for this is independent of
the connected passer bonus. Adjust various passed pawn related
scoring params.
2) Add engine console command for perft.
3) Adjust scores for Rook on 7th and make dependent on game phase.
4) Fixes to weak pawn scoring and outpost code.
5) Simplify and fix SEE function. Use variant version with quick exit
when only need to know if score is above or below a threshold.
6) Improvements to move ordering for check evasions.
7) Fix bad bug in lazy eval code of scoring module.
8) Bug fix: don't set the retrieved hash entry type to Invalid in
cases where the score is in bounds but moves have been pruned.
9) Bug fix: remove redundant increment of parentNode->num_try in searchSMP.
10) Further clean up & optimize pinned piece detection.
11) Static null margins & futility margins adjusted.
12) Fix KBPK draw detection.
13) Makefile support added for a popcnt-enabled 64-bit Windows build.

There are also updates to the opening book.

The engine .zip file now includes a popcnt-enabled build for Windows (for Intel Sandy Bridge or later). This also requires Windows Vista or later for the OS. There is still a non-popcnt build (arasanx-64.exe) that should run on older hardware and OSs.

I expect this version to be significantly stronger than 16.1 and the 15.x series.

--Jon