New chess engine: Equisetum 1.0

Equisetum - UCI chess engine written in C++11.

Equisetum uses Fail-Hard AB-search and NNUE evaluation. This approach resulted in an engine of moderate strength. One of the few strong engines using a fail-hard approach

Equisetum uses an NNUE (efficiently updatable neural network) as an evaluation function.

## Strength

Current Equisetum is estimated to be somewhere before Stockfish 11 and Stockfish 12 strength.

Equisetum 1.0 download