Arasan 17.0

Arasan 17.0 ... http://www.arasanchess.org/
Changes in Arasan 17.0:
1) A common hashtable is now used in both quiescence and non-
quiescence search, instead of using a separate q-search eval
cache (hashtable stores static evals so also serves as an
eval cache).
2) Scoring module no longer does lazy eval.
3) Opening book format has changed. Manual tuned book file is
now annotated PGN instead of a custom text format. Book code
is simplified.
4) Opening book is no longer modified at runtime by result and
score learning. Only position learning (aka permanent brain)
is supported now.
5) Improvements to opening book and ECO classifier.
6) Qsearch no longer does pre-selection of capture targets.
Qsearch forward pruning margin and logic changed.
7) Bug Fix: correct time field of "post" output for Winboard/xboard
(was off by factor of 10).
Bug fix: declare on startup for UCI that the tablebase type
option is "Tablebase type", not "TablebaseType".
9) Bug fix: check for previous move legal before returning draw
score.
10) Bug fix: Don't apply history pruning to moves before the
history phase of move generation.
11) Bug fix to KP + wrong Bishop vs. K draw detection.
12) Bug fixes to lockless hashing. But also: restore validity
check for moves fetched from hash, since lockless hashing
is not 100% reliable.
13) A few evaluation changes.
14) Improved debug output when -DSEARCH_STATS enabled.
15) Performance fix: remove unneeded update of node count at end
of search function.
16) Change to time usage: generally uses more time in early phase
of games.
17) Changes to razoring.

Overall this version is measurably stronger than 16.3 in my testing but it is not a huge difference. However, there are significant internal changes and I expect it will play differently from 16.3. The opening book is also significantly re-done in this version