[xmonad] The new decoration framework has been pushed

[Andrea Rossato]

Hi,

I've just pushed the new decoration farmework, with the floating
layout, the keyboard manipolation framework, and everything I've been
talking about lately.

I'll try to be as quick as possible in fixing bugs.

I've also pushed the LayoutCombinator class. This is will make
LayoytModifier(s) and LayoutCombinator(s) implementations totally
independent from the Layout implementation.

I'll write more extensively on that at a later time, also because I've
already said quite a lot in previous messages.

Hope you'll enjoy.

Andrea