Fix the style file for VClassSzPublic
Use the DynamicGridLayout in VClassSzPublic
Change the way FullUpdate works
Simplify RootItem by using NodeWrapper
Remove unused references to PositionLayout
Remove broken and unused code associated - PersistentNode

In the future is such functionality is needed, it should be implemented
as an intermediate interface directly in FilePersistence, and it should
be based on GenericNode.
Generalize GridLayouter::regions and use it in (the static) GridLayoutFE
Make the region generation by GridLayouter more flexible
Use GridLayouter also for generating the regions of SequentialLayoutFE
Change the NodeToId map from a singleton to a per TreeManager object

This is used to support loading multiple versions of the same project
project at the same time. These will contain many nodes with the same
ids.
Allow creating an 'if' by surrounding existing statements with if{ }
Enable loading of models from memory and not only directly from disk

UNTESTED!
Merge commit '57c22829db069e67b7b8ec0d2dd8e65e2d259162' into version-control