v2.0.0

Most of the gains in this release come from a better, less buggy neural network. There are also some performance improvements and minor improvements to search. This release is approximately 250 elo stronger than version 1.0 at short time control (8s+0.08).

The release binaries are categorized by microarchitecture levels. The general rule of thumb is:

x86-64-v3 will work on modern (2015+) CPUs (avx2, bmi1, lzcnt, etc.)
x86-64-v2 will work on older (2009+) CPUs (popcnt, sse4, etc.)
x86-64 will work on any x86_64 CPU.