Introducing Actions abstraction

Added Action interface and two base classes;
Grouped entities abstractions and implementations into Entities folder;
Sources separation

Moved libraries sources into separate repositories;
Introducing first action

Added PickUp and Attack actions;
Reworked ActionController, CUI and ActionService accordingly;
Prepare for evolution

Added available states and transitions for Creature;
Evolve

Added type parameters to Creature for it's state engine;
Added state engine property to Creature;
Added basic behaviours (in CreateController);
Changed Actions service and controller to use state engine;
Changed Create methods accordingly;
Restructure

Moved states and transitions to root and made them public;
Restructure

Extracted basic behaviours classes into separate files and namespace;