Workbench Model Tooling

While traveling by train to Vienna and back I had time to invest some time into the workbench tooling and I think I added some nice and helpful things.

• "Live" Model Inspection: The first and most important feature is that you can now inspect the model of your running workbench by hitting CTRL+SHIFT+I
• Better support for Window-MainMenu and Part-ToolBar
• Adding Support for Fragment-Tooling

The tooling is not as good as I had hoped to be at this point (e.g. taking part in renaming actions is not supported and I doubt to get this ready for the July release). I'll try to invest some more time into this but I need to feedback from people to find problems and missing features, ... . I can't guarantee to implement all of them but your input is crucial to at least fix the most important parts.