NEW : hide/show attribute

- the checkbox created in the GUI and implemented in ShapePopulationQT allows the ser to display or not the Attribute annotation
- in ShapePopulationBase, we created the same implementation than when hiding the scalarbar vector
- we renamed the displayInfo and displayAttribute functions in class QT to match the other update[...]_QT() functions of this class, so that we could use those names in ShapePopulationBase