Group all engine-related objects into Engine control class
Changes after API changed
GameView converted to interface
Changes after API change
Added widget to show the engine
Some cleanup in engine initialization
Avoid accumulating clicks in edition mode that have consecuences in test mode
Bug fix in touches component
Bug fix in EngineEntity
Fix MockEntitiesLoader to make work tests
Changes after rebase
comments addressed
Merge pull request #578 from anserran/enginewidget

Added Debug view to editor desktop, along with a widget to show the engine
Minor changes in the JavaDoc
Extract ActionListerner interface and EnableActionListener and create their own interface/class. Modify the references to these class/interface.
Minor changes in the JavaDoc
Add the support to ModelListener#modelChanged Action Clases (only in Paste and Save, the others have it already implemented)
Added new style class for IconButton and its corresponding implementation in light/skin.json
Modify createIcon and createItem methods to take into account the "enable/disable" state of the actions
Adatp the code to rebased changes in WidgetsUtil and include other methods in that class