Fix typos in unresponsive overlay

This component started as a WindowClientWindow child hence it was
using clientWindow rather than window.
Busy cursor when surface is unresponsive

This seem not to work when the compositor is in a X11 window though.
Automatically ping the surface after 10s when it's unresponsive

Let's handle this ourselves, a nice service to the user.
Explicitely use window to access its properties
Don't enable animations when mapping windows

It will be done at the right time.
Remove popup surfaces from model when unmapped

Popup menu surfaces (at least with Qt applications) are not destroyed so
their element is not removed from the surface model and the next time
the same menu is open, surfaceMapped() sees it and thinks it doesn't have
to create a window representation.

But we get an unmapped signal so it's there that we remove the surface
from the model and destroy its representation.
Destroy chrome along with window representation
Remove damageAll() calls

We don't have this anymore.
Emit signals when window animations are started or stopped

This let us do something when animations are starting or are done.
Reenable behavior animations when window animations are done
Zoom screen with Super+Wheel
Zoom screen
Move hot corner and screen view to a subfolder
Move hot corners to a separate item

Tidy the code.
Don't explicitely set the overlay layer z-index

Remove leftovers.