qmlui: allow to detect currentValue changes on ComboBox
qmlui: allow to detect currentValue changes on ComboBox

mcallegari/qlcplus,sbenejam/qlcplus,plugz/qlcplus,kripton/qlcplus,kripton/qlcplus,kripton/qlcplus,plugz/qlcplus,kripton/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,mcallegari/qlcplus,kripton/qlcplus,kripton/qlcplus,mcallegari/qlcplus,mcallegari/qlcplus,plugz/qlcplus,sbenejam/qlcplus,kripton/qlcplus,mcallegari/qlcplus,sbenejam/qlcplus,plugz/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,sbenejam/qlcplus,plugz/qlcplus,sbenejam/qlcplus,plugz/qlcplus,plugz/qlcplus