model added
Model connected to scene
#4580: Constructors upgrade

+ Moved back object ptr in visual objects.
+ It compiles with uncommented old methods at least. ☺
Node connection added
#4580: Model upgrade

- No exceptions when deleting/adding nodes found
- Converter works, but loses node's connections due to model system
- Minor bugs and performance improvements
#4580: Missed new GraphScene.h
#4580: No pointers link system, converter update
#4580: Model and scene splited at all, deletion and adding restored
#4580: Fixed links removing, node converting restored
#4580: rows() when using qmodelindex replaced to internalId()
#4580: Objects emit dataChanged() when the disconnect links
#4580: Nodes multiple deletion fixed
#4616: Splitted objects to visual/data.

Now visual objects are just based on real objects.
#4580: preventing link duplication (creating few links between two nodes)
#4580: Stabilized deleting of nodes on graph.

Also, about to locate how to delete links properly.
#4580: Adding/removing nodes/links fully working.
#4580: Made common logics for objects+simplifying
#4580: quint32 system + converter

Much more simpler logics came.
#4580: Links' annotations back to work.
#4580: Refactoring ended. (minor code improves)