First draft of Outline_Decompose

As I said in my last PR, I'm a complete newb with V8/nan and C programming in general. There's a lot of repetition and probably poor practices that should be cleaned up.

Notes/issues:

- Ideally I'd like to separate out FT_Get_Glyph for parity with the API. But `Glyph.c` is currently wrapping `FT_GlyphSlot` and not `FT_Glyph`, so I'm not sure what you want to do with that. 
- I'm passing the positions as individual arguments (e.g. easy integration with node-canvas `lineTo` and such). But if consistency with FreeType is more important, I could change to use vector objects.
- The functions are bound to global scope. Passing a "user" context as the last argument doesn't make much sense in JavaScript land (where we are free to rebind functions), but I guess it does keep it more consistent with FreeType. 
- I needed to add `ftglyph.h` and `ftoutln.h` as includes