Some compile time error fixes.
Added sprite atlas data file.
Added classes for SpriteAtlas data/parser/processor. Difference to
TextureAtlas is that the SpriteAtlas processes generic bitmapdata, not
Textures for use with Stage3D.
Changed placeholder image creation in resource index to be able to
directly obtain a placeholder image.
Made placeholderImage method static.
Added placeholder image fallback to SpriteAtlas.getSprite.
Added transparent and backgroundColor support to SpriteAtlas.
Added contains method to DataParser.
test compile.