Get rid of _MSC_VER #ifdefs

[louwers]

#270 introduced _MSC_VER #ifdefs in the source files.

I think it would be good if we good remove those from source files and instead configure the build tools to ignore those warnings. We should limit the platform specific macros from platform a-specific code as much as possible in my opinion. If we would do this for every platform there would be a lot of noise in the source files.

I'm not really familiar with Windows (cc @ntadej & @tdcosta100).

[ntadej]

I think sometimes they are just unavoidable and also we should not ignore warnings globally (unless obvious ones which we already have).

I have some personal stuff to deal with that's why I've been a bit inactive lately but I can hopefully have a look next month.