Models type rework part2 - First try
Another option for models management: alternative impl. for !55 (closed)
Finish the refactoring of models managed by the engine. Now, we have only 3 categories, in order of priority:
- Primary: everything, except below..
- Virtual: old CPU_VM
- Non-idempotent: NS3
ATTENTION: This commit changes the temporary API in Engine::add_model.