Clovis is born again!

• implemented gradient descent tuner
• disabled drawishness and some other evaluation functions until they are integrated into tuner
• added some params to evaluation (candidate passer, rook on seventh)
• vertically mirrored some PSQTs

Expecting a ~50 Elo improvement from Clovis II!

Clovis II joins the fray!

• implemented move count pruning
• use different thresholds for SEE based on whether or not quiets are skipped
• virtual king mobility heuristic
• queen promotions generated in capture stage
• precalculate more masks and tables
• more use of constexpr

Expecting a 50-70 Elo improvement from Clovis I

The changes since v2.0 are not really worthy of a new release, but I've decided to make one anyway as I realized it would be on-brand to start using roman numerals for the versioning of Clovis.

Eval is no longer called when the king is in check, and enemy rooks are now considered transparent for bishop mobility and king safety.