Precompiled DLL for release 64 bit also

[TheMercer]

So precompiled 32 bit is already there for last few releases.

I use 64 bit version often. I can compiled myself which is fine. I think be nice to have a 64 bit version also.

[dzalkind]

We rely on conda to compile and maintain the libraries across platform, except 32-bit Windows: https://anaconda.org/channels/conda-forge/packages/rosco/overview

There are utilities that can extract the libraries from the .conda archives. Maintaining these libraries manually might be out of scope for the current maintainers.

I'll leave this open until I add clear instructions for users to grab pre-compiled libraries.

[dzalkind]

This will be addressed in #503