Update docs

* Remember width after resize in HalfLayout

* Add a shortcut to toggle window borders

Remove an additional layout.activate and movestep handling (only in
tilingmanager) as they do _nothing_

Defaults to Meta+U

This means you can now resize it, close everything, and it will keep the
width ratio

This only applies to the focus hotkeys

This includes error checking and initializing variables to proper values

This also introduces a proper method to add clients to a tile and remove
clients from it which
allows us to do sanity checking

Previously, it was possible to go down from tile 0 to tile 1, but not up
from 1 to 0.

Now, don't allow going down from tile 0 (as it's not actually down).

* Retile on layout switch
* Keep desktop floating even on switch
* Error checking (more)

This is literally a one-line change.

* Enable resize animations
* Fix resizing bladelayout
* Fix panel adjusting (with a workaround)

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