Clip engine view
Simplified structure to relate EngineEntity and Actors

Now, instead of each EngineEntity having a group that has a child
which is the renderer, the renderer is directly associated to the
EngineEntity.
Added a default container in group editor

So panning/zoom isn't performed over the scene container directly,
which was provoking some side effects.
Tests fixed after changes
Refactor TouchListener
Merge pull request #620 from anserran/sceneedition

Some fixes in scene edition, along with clipping in the engine player
Load libraries from local if available.
Small fix while performing EditScene action.
Improved RepositoryGallery.
Code cleaning.
Fit groupEditor while editing.