Implemented new command/event for detecting and adding newly created windows
New windows are now (somewhat buggily) added to the current tiling layout
Removal of windows partly implemented

 - Currently not working as windows are not getting removed correctly (seems
   to be a problem with window equality checking for removal)
Creation and destruction events are handled

 - windows now get added to and removed from tags when created and destroyed
 - Some further tweaks required (eg windows explorer does not get destroyed
   correctly)