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
Fixed some i18n strings
Added the icons of repository downloads, Timer and Touch.
Also added the vectorial images.
And replaced Behaviour by Actions. In spanish "Comportamiento" was too long
Style cloned for button, imagebutton, label and textbutton processors.
skin and cool demo updated
Merge pull request #517 from jtorrente/fix-476

Fixes 476
Merge pull request #515 from RotaruDan/BehaviourPanelImprovements

Behaviour panel improvements
Format
Better handling of shortcuts
Refactor associated to changing ShortcutsMap
Added desktop shortcuts
Bugfix in ViewsHistory
Updated Clipboard to use selection instead of asking views
EditorGameAssets sets components ignores

Clipbard also needs to serialize objects with editorGameAssets, so Save
can't set the ignores no more.
Updated Copy, Cut and Paste actions