Adds the documentation to all the GERenderers,
Renames the GERenderer abstract class into SimpleGERenderer,
Creates an interface GERenderer,
Changes the method render(GraphicalELement, CompositionJPanel) into render(GraphicalELement),
Adapts the CompositionJPanel to the previous modification.
Corrects a bug for the ListCA, the selected value configured by the user was not saved.
Adds documentation to several files.
Does a lot of Refactoring to make the names more explicit.