Added GroupEditorConfiguration to group editor widgets.
Added longPress event in MockupSceneEditor.
Cleaner icons
Small Scenes bugfix.
Improved EditorGameAssets#resolve(String) method
EditorGameAssets now loads engine skin.
Reduced the size of buttons and added new icon.
Added panel in scene edition with next options:
	Delete selected elements
	Move to back or front the selected elements
	Go to edit element
- addComponent moved from EntitiesLoader to ComponentLoader and made public
- AddComponentExecutor now uses ComponentLoader.addComponent instead of creating components by itself
Accommodating to changes in API
Merge pull request #556 from jtorrente/fix-514

Fixes #514
Merge pull request #548 from RotaruDan/fixes

Small Scenes bugfix.
Merge pull request #549 from RotaruDan/editorAssetsSkinLoading

EditorGameAssets skin loading
GroupEditorConfiguration refactoring and javadoc.
Merge pull request #541 from RotaruDan/SceneEditorExtension

Added GroupEditorConfiguration to group editor widgets.
Adding more than one valid arguments in Action
Merge pull request #559 from angeldelblanco/action-bidimensional-validation

Adding more than one valid arguments in Action
Merge pull request #547 from anserran/newicons

Cleaner icons
name field added to repo element
Merge pull request #560 from jtorrente/repoelement-name

name field added to repo element