* re-designed the information/properties panel to show meta information and statistics

* re-designed the information/properties panel to show meta information and statistics
- the display of meta information is completely implemented and functional
- the tree-view in the "Advanced Info" tab is currently broken due to bad casting (I got no idea why yet, because I didn't touch it..)
- the statistics tab isn't implemented yet

Comments on the design and the implementation are welcome. If this re-design is too unstable for 0.8.5, I will withdraw it after branching.