Windows support

[nilsnolde]

I tried building prime_server first time last night on Windows.

Of course there were quite a few build failures, but most very trivial to get around. I'll keep this as a log for myself mostly, not asking anyone to take action. But of course I'd appreciate ideas if any come up:)

TODO:

• include:
  • winsock2.h
  • dirent.h
• some compiler definitions missing, e.g. NOGDI, WIN_LEAN_MEAN, some others I think

Blockers

• Windows has no notion of signals, which I guess would be a big one as that's an important communication mechanism

Alternatives

Instead of a native MSVC build one could explore a MinGW64 build. I read somewhere that *zmq compiles fine with MinGW, even on Windows. Even nicer might then be cross-compiling it on Linux for Windows. The one blocker there is, might very well makes this most feasible route.