NOTE API change!
 What has changed:
  - 'sprite' style is now index value not a reference to an Image element - instead references textures list on parent emitter.
 Why did it change:
  - Because it ensures 'style' objects are always serialisable (plain JavaScript string/int/boolean properties only) and can be merged by a simple object combine.
 How to migrate:
  - Find and Replace use of:
obj.style.sprite = bitmaps[0];
    with:
obj.style.sprite = 0;
obj.textures.push(bitmaps[0]);

Implemented emit light polygons and object style (glowing).
Live debug example test scene - see test1d.html
obj.style.geometrysortmode implemented.
'sprite' style is now index value not a reference to an Image element - instead references textures list on parent emitter.
Added static helper to generate a basic entity 'style' structure.

(svn r636)