pluginType dialog doesn't seem to terminate upon closing

Something is quite off, at least when running plugins from the Plugin Creator.

Setting a breakpoint in void PluginCreator::closePlugin() shows that the function is indeed not called when using the close button from the dialog.
Furthermore it also shows that the function is called the same amount of times as you've ran the plugin from within the creator.

This leads me into thinking that the plugin isn't destroyed when it calls Qt.Quit() (and perhaps it shouldn't be, open for suggestions). But each time you click run, a new QQmlComponent, QQuickView (and possibly QDockWidget) is instantiated, while the previous instance is lingering somewhere.
Each time, the quit signal from the qml engine is attached the same handler as well:
connect(qml, SIGNAL(quit()), SLOT(closePlugin()));
which explains the multiple calls to closePlugin.

Proposed fixes:
1. disconnect closePlugin from qml.quit in closePlugin -> prevent multiple calls
2. figure out why the view isn't destroyed when quitting, possibly destroy it in closePlugin
-> what other items would need cleanup? the underlying QQmlComponent?
3. figure out the correct signal to listen to from a dialog and connect that one to closePlugin (possibly the QQuickWindow::closing signal)