Adds doRectFloat, which floats the new window in the given rectangle; and doCenterFloat, which floats the
new window with its original size, but centered.
The initial patch that extended the EDSL for writing ManageHook rules did not come with a good example on how to use it. This patch ammends that. 'move' is an example of how to write a rule to resolve a Query (Maybe a) into something tangible. 'move'' is an example of how to write a rule isolating window managing code from the rest ofthe mess the EDSL creates.
This patch adds a few types of relationships and operators for managing windows with rules. It provides grouping operators so the X action can access the quantifier that was matched or not matched. It provides a formalism for predicates that work in both grouping and non grouping rules. It could do with some classes, so that there are fewer operators that always do the Right Thing (TM), but the Haskell Type system currently has some problems resolving types. Since I don't know enough about these high level things, it would be hard to create a GHC patch just to make it all work.
