- boo#1218288: Require liblxqt
Panel plugins can depend on lxqt-backlight_backend

- Update to 1.4.0:
* Use lxqt-menu-data instead of lxmenu-data.
* Fixed checking/clearing of urgency in task bar.
* Fixed window cycling with mouse wheel and focus stealing
prevention in task bar.
* Added parameter parsing to launched command of volume plugin.
* Fixed the initial displayed volume with PulseAudio in volume
plugin.
* An option is added to the custom command plugin for showing
the output as an image.
* Added a clear button to the search bar of Add Plugins dialog.
* Fixed the tooltips of volume control under Wayland.
* Prevented a crash on Wayland.
* Some code cleanup.

- Update to 1.3.0:
* Small problems are fixed in the seconds shown by the clock
widget
* DOM plugin is enabled by default
* Some code cleanup