added xmonadwide layout; min-max ratio and min_width are now configurabl...

while migrating from awesome to qtile, a horizontal layout was important for me; so i've cloned xmonad and changed it to adopt the horizontal layout: xmonadwide.

I've also expressed the need of a configurable min_ration and max_ratio, the default 25% was too much for me, so now you can pass this parameters in config like:
`MonadWide(ratio=0.7, min_ratio=.10, max_ratio=.90)`

the configuration max_ratio, min_ratio and min_height is also appliable to the original xmonad layout.