Fixes unexpected error after opening an imported game.
Improves cloned scene name.
Fixes Credits link.
Merge pull request #783 from RotaruDan/openGameFix

Fixes unexpected error after opening an imported game.
Merge pull request #784 from RotaruDan/clonedSceneName

Improves cloned scene name.
Merge pull request #785 from RotaruDan/smallCreditsLinkFix

Fixes Credits link.
Using Engine Initializers to better stablish components processors
Merge pull request #786 from anserran/refactorempty

Refactor in EmptyRenderer
Get text input the first time a text is added to the scene.
Merge pull request #787 from RotaruDan/newEngineFont

Get text input the first time a text is added to the scene.
Adds ExtendedSkin and ExtendedSkinLoader to engine-core.
Solves pom dependencies.
Merge pull request #788 from RotaruDan/newEngineFont

Adds ExtendedSkin to engine-core.
Now the button in top toolbar plays the current scene and the play button in navigation pane plays the first scene.
Merge pull request #791 from gorco/playButtons

Now the button in top toolbar plays the current scene and the play butto...
Added changes in clipboard to allow paste a list of objects in the same action.
Allowed remove all selection in mockup and removed unused clone action.
Allowed add and select a array of entities
Limited sound extensions to .mp3, .ogg and .wav
Add sort by date as first option in SortWidget.