Support for AWD format (Away3D)

About AWD format :
http://awaytools.com/awdformat/

In short, it's a lightweight format, faster to load, faster to parse than all ascii/utf based 3D formats.

A first draft version of parser is available on this fork 
https://github.com/plepers/three.js/tree/awdloader
(has been developed to run with [modified version](https://github.com/plepers/three.js/tree/specialt) of Three.js)


The first step is to cleanup the actual version, in order to make it work on the actual dev branch, with minimal features :

 - ~~parse geometries as BufferGeometry~~
 - ~~parse meshes instance as Mesh~~
 - ~~parse containers as Object3D~~
 - ~~find a way to handle meshes with multi-materials (away3D feature)~~
 

next steps :

 - handle primitives
 - support for morph and skeletal animations
 - lights and cameras
 - materials and embed textures?
 - ...