Added layer ids to a separate class so it can be easily referenced from GameLayers but also from outside
GameLayers refactored:
- Flexible layer-structure independent design. We can change how layers are arranged by adding/removing/editing Layer class
- Added a method for clearing layers but preserving layer structure
- Methods renamed to sth that suits them better
Simple test for layers
EntitiesLoader refactored:
- GameLayers has been taken out from EntitiesLoader. Now EntitiesLoader just loads the elements, but don't get them actually added to the view.
- Public methods have been renamed to a better choice. Now we have two methods: "loadEntity" and "toEngineEntity".
- Javadoc improved
GameLoader and GoSceneExecutor refactored after latest changes in the API
Other refactorings
Comments addressed
Merge pull request #513 from jtorrente/gamelayers

Tidying up game layers and entities loader