Buster 7.0.2

Requires a CPU with BMI2 (Intel Haswell or newer, AMD Zen). Runs very slowly on AMD Zen 1/Zen 2.

Windows support. Search and evaluation are unchanged: on Linux, 7.0.2 searches exactly the same
nodes as 7.0.1, so the 7.0 rating applies.

• Prebuilt binaries for Linux x86-64 (fully static) and Windows x86-64, and a make release
  target that builds both (the Windows one with the MinGW-w64 cross-compiler).
• 64-bit-safe on every platform. On Windows a long is only 32 bits, which silently cut
  bitboards in half. Bit counting now uses the standard C++20 <bit> functions, and 64-bit constants
  are unsigned long long, so the code means the same thing everywhere. The Windows build passes
  the self-tests and matches the Linux perft counts and search node counts exactly.
• Builds as C++20.