Adapt to new boolean operation interface

[rainman110]

With occt 6.9.0, the new boolean operation interface has many benefits:

• Fuzzy BOPs. These should help in case of coinciding faces. (BRepAlgoAPI_BooleanOperation::SetFuzzyValue)
• BOP with multiple shapes simultanously (BRepAlgoAPI_BooleanOperation::SetArguments and BRepAlgoAPI_BooleanOperation::SetTools)
• Integrated intersection computation (BRepAlgoAPI_BooleanOperation::SectionEdges)
• Progress indicator support (BRepAlgoAPI_BooleanOperation::SetProgressIndicator). We could provide a callback interface for the progress. External Applications like TiGL Viewer could use it, to display progress bars etc...
• Parallel BOPs (see issue #113)

These features are really great and are beneficial for TiGL. If we adapt TiGL to the new interface, we can simplify our code and provide potentially a more robust solution.