Port blackhole to Visual Studio 2017

[Maturin]

blackhole does not build with Visual Studio 2017. (I haven't tired it yet, but my educated guess is, other Visual Studio compiler won't work either.)

More or less a prerequisite for implementing this issue are #186 and #188.

[Maturin]

@3Hren: I pushed my changes to my repo. It would be great, if you could already a look at it.

Primary what is left do are some cleanups. Especially I want to replace reoccurring constructs like the one below with calling a function, which does this only one time for each system function. In total I had to do this for 4 system functions.

#ifdef _MSC_VER
    ::gmtime_s(&tm, &time);
#else
    ::gmtime_r(&time, &tm);
#endif