Performance improvement + other stuff

- Performance improvement by iterating file directories with the
Parallel Class (according to
http://msdn.microsoft.com/en-us/library/ff477033(v=vs.110).aspx)
- Animation is no longer freezed on getting directory content (due to
running FillFileSliceWithDirectoriesAndFiles() in a separate thread)
- Still TODO: Loading animation in NodeActivationAnimation()
- Deprecated VSync replaced with SwapInterval
- DisplayLists are now pre-generated in OnGlwidgetInit() by
GenerateDisplayLists()
- .NET Framework updated to v4.5
- SkyBox animation (rotation) added
- Trace added to Util
- ShowDetails set by default to not visible
- Fullscreen mode can now be enabled in MainWindow Constructor (it's
disabled by default for easier debugging)