finished working on unique names :
- when created a nested node is directly added to the model with modified default name if it is already taken
- when node name is updated, model name is updated as well except if already taken
TODO : look at node deletion on model
NOTE : this system of unique name may change in future development iteration : two nodes could have the same name and refer to the same subgraph tactic, name changes could lead to copy/delete actions etc.