merged develop branch from yanhick repo
removed obsolete files
block and inline formatting context now only have 1 instance per document
converted more typedef to value objects
reducing rectangle and point instantiation
reducing rectangle and point instantiation
removing uneccessary instantiation
there is now only one instance of each box computer per document
removed obsolete files and reduced point instantiation
added invalidation to layer renderer for compositing
improvement in layerrenderer
implemented classlist
bug fix for visible style and in cascade
bug fix in intrinsic height computing
actually commit bug fix
bug fix absolutely positioned element use padding box of containing block
fixed bugs in line box background
bug fix for sound with no ID3 tag embedded
bug fix in layerenderer, bitmap data size wasnt always updated
bug fix, text was in some condition rendered twice