Add CheckListPrompt to quickly.prompt

[Rick Spencer]

This is generally useful code, should be built in:
class CheckListPrompt(Prompt):
    def __init__(self, title = "Input String", text = "Input a String:", default_value = None):

        Prompt.__init__(self, title, text)
        if default_value is None:
            default_value = {}
        self._vbox = gtk.VBox(True,5)
        self._vbox.show()
        keys = sorted(default_value)
        for k in keys:
            cb = gtk.CheckButton(k)
            cb.set_active(default_value[k])
            cb.show()
            self._vbox.pack_start(cb)
        self.content_box.pack_end(self._vbox, True, True, 5)

    def get_value(self):
        return_dict = {}
        for c in self._vbox.get_children():
            return_dict[c.get_label()] = c.get_active()
        return return_dict

def checklist(title = "Input String", text = "Input a String:", default_value = None):
    clp = CheckListPrompt(title, text, default_value)
    response = clp.run()
    val = clp.get_value()
    clp.destroy()
    return (response, val)