TCP Native development

I'm not opening this for a merge straight away, although the tcp test works fine so far on windows/linux, but I'm hoping for a little help on the Linux epoll compilation times right now. It takes 93 seconds on a Xeon E5-2620 core with Fedora 20 x86_64. 

The Windows IOCP implementation takes less than 2 seconds to compile though, and it does pretty much the same thing.

I'm on git master

@MartinNowak could you take a look real quick at why dmd is taking so long?