NAN 1.5 WIP

This branch will become NAN 1.5.
Added Asyncworker #207 and new NanNew #210. Needs more testing with actual addons.
Now split into many files. Seems to work so far. Good news for nauv.h
Hey, why not omit the "public" and use struct instead of class? Struct inhearitance is public by default, isn't it? Sry C++ beginner comment ;)