OCC.Utils _really_ is no place for DataExchange

is showing a poor sense of structure ( how is data exchange, loading CAD files a utility? )… very counterintuitive…

I've added a fast loading STL module.
Something rather silly in the other STL.py is that the STL mesh is converted to BRep's… so this explains the _very_ poor performance of STL.py
Therefore its a very good idea to have "XSDRAWSTLVRML_DataSource" wrapped before releasing 0.6, since then this version should become the default STL loader.
Its 10 - 100* times faster ;)