Optimise the shape reconstruction process

[bchevalier]

The processShape method (in SwfObjectProcessor) reconstructs vectorial paths from the swf vectorial drawings. The structure that stores the vectorial drawings in SWFs is special for 2 reasons: it is compressed and it is compatible with their rendering engine (that treats edges between 2 fills of a same shape as a special case for better quality).

The processShape method can probably be optimised to parse the vectorial drawing structure of swf objects more quickly.