Corrected AxisBuilder to remove properly the visual group

src/main/java/fr/ill/ics/n3d/gui/AxisBuilder.java

@@ -123,7 +123,7 @@ public class AxisBuilder {
 	 * @param modified true if the axis was modified, false if it was added
 	 */
 	public void stop(boolean modified) {
-		if (!modified && this.axis != null && this.parentGroup != null) {
+		if (this.axis != null && this.parentGroup != null) {
 			this.parentGroup.getChildren().remove(this.axis.getVisualGroup());
 		}
 		this.axis = null;