Simplify a condition in gives_check()

Now that aligned() is quite fast we can skip
some logic.

No functional change.
Rename CASTLE to CASTLING

It is call 'castling move', not 'castle move'

Noticed while reading DiscoCheck sources.

No functional change.
Report high evaluations instead of mate in 50+x when a tablebase win has been found. Once the root position is in the tablebases, report a score indicative of the tablebase score for the root position.
Merge remote-tracking branch 'upstream/master'
Assorted spelling fixes

No functional change.
Big assorted spelling fixes

No functional change.
Merge remote-tracking branch 'upstream/master'
Another round of spelling fixes

And also renamed a loop variable while there.

No functional change.
When drawing due to the 50-move rule, let the score indicate how close
the position is to a win (or loss). This only works if the root position
would be won or lost had the move counter be 0. The closer the reported
score is to 0.50, the closer the position is to a win.
Re-fix a comment

No functional change.
Merge remote-tracking branch 'upstream/master' into syzygy1
Merge remote-tracking branch 'syz/master' into syzygy1