Common base class

Currently both DynamicCore and StaticCore extend HybridCore. This is a bit strange inheritance hierarchy in general, but it's especially stupid to check does a library extend any of these by using isinstance(library, HybridCore). It would be better to have a common base class named LibraryCore or RobotLibraryCore that all concrete lib cores extend. It would allow using isinstance(library, RobotLibraryCore).

Until this common base class is implemented, it's probably best to use isinstance(library, (HybridCore, DynamicCore, StaticCore)) with any generic code. That's both more explicit than just using isinstance(library, HybridCore) and also works if and when other cores don't anymore extend HybridCore.

Inizia individuando le definizioni e gli utilizzi di HybridCore, DynamicCore e StaticCore. Esamina in che modo un LibraryCore o RobotLibraryCore condiviso influirebbe sull’ereditarietà e sui controlli generici con isinstance; il lavoro è completato quando i core concreti condividono la nuova classe base senza fare affidamento su HybridCore come tipo comune.