Make Negatus build and mostly work on Windows with MSVC

Pretty straightforward, I fiddled the Makefiles a bit to make things easier for myself. We could collapse them back together without too much effort but I didn't feel that motivated.

Visual C++ doesn't like initializing stack arrays with variable size, so I changed all instances of those to std::vector<char>.

I didn't implement a few of the time commands (uptime, settime) and I forgot to implement kill. I don't think ps actually works properly either, since it's parsing the output of ps. A few of the other commands don't work because they're Linux or Android specific, but that's no worse than the current state on OS X either.
Using strdup(line.c_str()) would guarantee the null terminator and should be more efficient than constructing a vector here.