- Fix X11 backend to return zero score on non-X11 platforms

If preferred backend is set try it first.
Do not set preferred backend automatically. It must be user choice.

- Split XDG_CURRENT_DESKTOP
- Skip LXQTPANEL_PLUGIN_PATH if empty

libwmbackend_<platform>.so

NOTE: works only on KWin

- Choose backend at runtime
- Windows filter logic is re-evaluated on window property changes

LXQtTaskBarPlasmaWindowManagment: implement showDesktop()

LXQtTaskbarWaylandBackend: do not show transient windows

LXQtTaskBarPlasmaWindowManagment: fix destructor TODO

TODO: is this correct?
Seems to call wl_proxy_destroy underneath

LXQtPanel: basic virtual desktop support on Plasma Wayland

Add desktop file to be recognized by KWin Wayland

NOTE: absolute path is needed inside .desktop file for this to work
      use CMake to get it.

- Prevent double dekstop file installed in autostart

LXQtTaskbarWaylandBackend: return only accepted windows

- reloadWindows() force removal and readding of windows

This fixes changing windows grouping settings and adding taskbar plugin
AFTER panel is started.
Both situations resulted in empty taskbar previously

LXQtTaskbarWaylandBackend: fix workspace logic

LXQtTaskbarWaylandBackend: fix workspace removal logic

LXQtTaskbarWaylandBackend: implement moving window to virtual desktop
workspace

LXQtPlasmaWaylandWorkspaceInfo: fix signedness comparison

CMake: move panel WM backends to separate libraries

LXQtTaskbarWaylandBackend: possibly fix crash on showDesktop for non-
KWin

Update license headers

LXQtTaskbarWaylandBackend: add dummy setDesktopLayout()

Implement LXQtWMBackendKWinWaylandLibrary

- Add Desktop Environment detection

…TODO

TODO: is this correct approach?

TODO: show error message when not supported

- Add NoDisplay=true to .desktop file

CMake: rename autostart desktop variable