Harmonize GridLayout2 and GridData2 with SWT classes

Similar to https://github.com/eclipse-windowbuilder/windowbuilder/issues/963, the [GridLayout2](https://github.com/eclipse-windowbuilder/windowbuilder/blob/master/org.eclipse.wb.rcp/src/org/eclipse/wb/internal/rcp/model/layout/grid/GridLayout2.java) and [GridData2](https://github.com/eclipse-windowbuilder/windowbuilder/blob/master/org.eclipse.wb.rcp/src/org/eclipse/wb/internal/rcp/model/layout/grid/GridData2.java) are old copies of the SWT layouts, which store additional information that are relevant during design time.

We should separate the designer information from the layout algorithm to make sure that our implementation matches the actual implementation.

Comienza con org.eclipse.wb.rcp/src/org/eclipse/wb/internal/rcp/model/layout/grid/GridLayout2.java y GridData2.java; después compara el trabajo relacionado en issue 963 y las clases SWT correspondientes. El cambio estará completo cuando la información específica del diseñador esté separada del algoritmo de layout y la implementación coincida con el comportamiento de SWT.

Escrito por el modelo de indexación a partir del texto del issue.