Make text in FIJIModalDialog optionally scrollable
Many dynamically created error messages would create windows that might even be higher than the user's screen. Instead of boundless growing this patch creates scrollable panes for the dialog's text on default, which can be disabled via the new '-scrollable' option. Scrollable dialogs will also be made vertically resizeable while others remain fixed-sized. The about dialog of FIJI Setup is made unscrollable to attain a suitably sized window.