We always seem to get the full area when we ask for a desktop that's not
the first (0).

These may be janky, but offer useful feedback.

- Bugfixes

Turns out it really _was_ needed.

It's better to be notified when something goes wrong than for it to be
ignored silently.

This is completely unnecessary.

This means a huge speedup when you do silly things like make a client
fullscreen and not fullscreen fifty times.

The issue was that we never got a tile when the signals were
launched (this could have caused other issues as well).

This currently does nothing useful (the outline is shown, but flickers
terribly), so don't waste the users CPU.

The former was broken in a previous commit, the latter is now properly
introduced (as shaded windows still report the same geometry, we handle
them as we do fullscreen windows - not).

Until now, the windows would leave a hole the height of the strut

For now it's the same in all layouts anyway (and untested, since kwin
doesn't seem to hand the new area)

It is _strongly_ recommended for now to use FocusUnderMouse with this,
as it's otherwise almost impossible to tell which window is focussed.

Should also fix e.g. Firefox resizing.

This also seems to already work in spirallayout (props to Matthias), so
now everything should work with panels _everywhere_, but still with restarts.

This needs to be fixed in the other layouts as well

This needs a couple of workarounds:

- Qt won't convert a QStringList to an Array, instead giving an utterly
  useless QVariant(QStringList) (without any methods and presumably only
  containing the pointer)

- The config group _needs_ to be empty, else it's not accessible from
  the javascript side

Always set tiling_floating.

This is untested, as it isn't even hooked up to anything yet.

This allows moving tiles with the keyboard.

This removes any remains of the idea of a "floating tile".
We're not a window manager, we just need to care about tiling windows.

(Also removes superfluous keepBelow setting)