VSEARCH 2.3.1 Windows pre-release

This is a pre-release of VSEARCH 2.3.1 for 64-bit Windows. The binary is compiled with the mingw-w64 cross compiler. Not tested well. Not for production. Feel free to try it out!

For support for gzipped or bzip2'ed files you need the zlib1.dll or bz2.dll libraries.