Attach clients below the currently focused client.
Merge branch 'wsmenu'.

Introduces two sets of keys; blocks all actions to underlying windows.
BIG REFACTORING.

This is still one big mess, so don't even bother.

Mostly consists of renaming functions to make it cleaner; updatewsd()
has had some additional changes, but they will get overthrow soon, so no
need to give a deeper explanation or to get a deeper understanding for
this.