Fix compilation on MSVC.

[pechy]

Compilation with MSVC fails because of the 'and' keyword, after replacing it with '&&' it works.

[bshoshany]

Hmm, it looks like MSVC does not interpret and as && unless the /permissive- or /Za compiler flags are used. That's my bad, I usually check that the code compiles with GCC, Clang, and MSVC before releasing a new version, but I didn't check with MSVC last time.

I release my projects in cumulative updates after editing them locally, so my policy is to not accept pull requests. Instead, I will merge this change into the next release, possibly together with some other changes, and along with a version bump and a corresponding note in README.md. Thanks for your contribution :)