This branch holds some work-in-progress patches that add a few things to the scripting API for use with bismuth, a tiling addon implemented as a kwin script.

• emit a workspaceDestroyed signal when kwin is exiting (so we can know to keep the window state information and restore everything after kwin restarts)
• (TODO) expose the read/write property window.hidden (so we can implement changing virtual desktops on a per-monitor basis)
• (TODO) yet to be determined