Merry Christmas!! 🎄🎁🎅

This (small) release is mostly search patches, such as cutnodes, fail-firm RFP, less futility, and other tweaks, with a new net.

In standard chess, this release is 76 elo stronger in selfplay, and 65 elo stronger in a gauntlet against other opponents of similar strength.

Elo   | 76.45 +- 15.76 (95%)
Conf  | 5.0+0.05s Threads=1 Hash=8MB
Games | N: 1002 W: 372 L: 155 D: 475
Penta | [2, 56, 202, 205, 36]

In DFRC, this release is 84 elo stronger in selfplay.

Elo   | 83.76 +- 15.78 (95%)
Conf  | 5.0+0.05s Threads=1 Hash=8MB
Games | N: 1002 W: 382 L: 145 D: 475
Penta | [9, 60, 179, 191, 62]

Based on the strength gains, v2.20 should have a blitz elo of about 3400, LTC elo of about 3280, and FRC elo of about 3590 (on CCRL scales).

A note on executables: Different executables for windows have been compiled for different instruction sets. AVX512 is the fastest, followed by AVX2, and POPCNT. Pick the fastest one that doesn't crash on your computer.