Re-organize Model packages, ScalaDoc

[maldins46]

As a final effort to define the model's basic structure, we are going to re-organize the model packages, in a way that makes clearer the behavioral implementation. In addition, we are going to finish the ScalaDoc in our part (model, interpreter, reducer, resolver).

[maldins46]

This morning we worked on a heavy refactoring of the terms used into the model, as stated in 2a1877e, and finished the Model ScalaDoc. In particular:

• Keyword behaviorable has been changed to BehaviorBased. This is a big change as involves a lot of classes.
• Modified the package structure. Now, behaviorBased is the only child package of Model, containing all the behavior-based-fashioned implementations. The package presents common as a child, at the same level of a impl child, that contains a standard implementation that makes use of common.
• impl packages now contain classes named Simple*, as it is a common pattern across the project. This can be discussed, and maybe some other keywords could be used;
• Other minor refactoring to maintain coherence between terms such as Triggers becoming ItemTriggers, Behavior becoming ItemBehavior, equivalent refactoring for Ground;
• ItemRef has been split from the ItemRetriver. ItemRef something that belongs to the Model, meanwhile the ItemRetriver is a concept used only inside the Interpreter. Then itemRetriver has been renamed to RefToItem.
• Direction enum is now included into the Room companion object, as it is a proper concept of the Room. Directions are not an enum anymore, but case classes of a trait Direction, making eventually possible to the storyteller to introduce their proper directions.

In light of these changes, we should also update the Ubiquitous language.

[maldins46]

As the last thing remained, we should finish the pipeline Scaladoc.