- Added a new Drawable interface.
- Entity class now inherits from Drawable.
- Added a Transformable abstract class.
- Now Mesh also inherits from previous Transformable class.
- Removed Mesh::getCentroid() getter. Use instead centroid().
- Added a new EntitiesSet template class.
- Getter getCentroid() has been renamed as centroid() in some classes.
- Some transformation methods have been moved from Entity class to Transformable.
- Added methods rotateAroundPivot() and scaleAroundPivot() to Transformable class.
- Added missing method EntitiesSet::draw().