Window Specific Commands work on workspaces

The command will be run all in windows in the matching workspace. For example,
[]s shades all the windows in the current workspace (an alias of <>s).
Can activate more than on window at a time.

Only the last window was activated remains active, which is system dependent.
Remove Null objects and handle Parse errors better

Instead of passing a empty dictionary to the Runner object. Just don't call the
Runner object at all.
Update DEVELOPERS with additional resources and remove wimsh ref
Clear wim-gtk after command is run