Added the getNumOptions() member function, which returns the number of option buttons in an option menu.

The setCurrent() and setCurrentNo() member functions now accept an optional second argument (notify). If notify is TRUE, the option menu will send a SEL_COMMAND message to its message target with message data indicating the new current option number (an integer).

Renamed the setPopup() and getPopup() member functions to setMenu() and getMenu(), respectively.