Double Impact of Gain tables

Very unorthodox idea.

After 16000 games at 60"+0.05
ELO: 3.14 +-3.4 (95%) LOS: 96.6%
Total: 13407 W: 2278 L: 2157 D: 8972

bench: 4705335
Don't early stop if we have a mated score

No functional change.
Revert "Double Impact of Gain tables"

This reverts commit 36c82b751ce227c05bfb

Seems a regression against 2.3.1 tested with 20K games at 60"+0.05

With patch applied
ELO: 15.44 +-2.8 (95%) LOS: 100.0%
Total: 20000 W: 3928 L: 3040 D: 13032

Without patch applied
ELO: 18.76 +-2.8 (95%) LOS: 100.0%
Total: 20000 W: 3903 L: 2824 D: 13273

bench: 4781239
Lower minimum allowed TT size to 1 MB

Setting a very low TT size could be used
for some specific testing.

No functional change.