Grille: hide Alpha or Beta depending on grid type

src/app/formulaire/definition/concrete/form-grille.ts

@@ -56,6 +56,8 @@ export class FormulaireGrille extends FormulaireBase {
                 this.reset();
                 // Inclined grids have more input fields (OEntH and cIncl)
                 this.getFieldsetById("fs_grille").updateFields();
+                // Alpha and Beta are not always shown
+                this.getFieldsetById("fs_plan").updateFields();
             }
         }
     }