enable static build for windows

[JupiterRider]

This should solve #409

[eXpl0it3r]

Just changing the runtime linkage for CSFML won't help, as SFML also would rely on the runtime. But we intentionally prevent the static linking of the runtime when building SFML or CSFML as shared library, because you'd otherwise include a different version of the runtime in each SFML module DLL. For CSFML that would duplicate everything again, i.e. each CSFML and each SFML DLL would contain its own version of the runtime. This will eventually cause issues at the boundaries.

In the past we would link SFML statically into CSFML, but this then causes issues with singletons, see #136 (comment)

I guess the solution would be the package the runtime into the NuGet as well, given that Microsoft doesn't seem to offer an "install runtime" option for NuGet, nor do they provide the runtime as NuGet package.

[JupiterRider]

I cam closing this in favor of #412