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
>The word 'struct' is one letter longer than 'class' pushing the line width to 81.

Yes, I got that. But omitting the word "public" because struct inheritance is public by default saves 6 letters + 1 whitespace. So this could be consistent.