qtdeclarative example 'mousearea-example.qml' should be enhanced, showing qt's ability to handle MANY mouse buttons.

With Qt 5.0 supporting up to 28 mouse buttons, we should show that it is possible to use them in our example. This BugID tracks creation of a revised example, increasing the number of mouse buttons from 2 to 10 (i.e., Qt::ExtraButton7).