Drop some unused globals and command line switchers, notable changes
--indirect-rendering : There isn't a sane usecase for this anymore apart from remote compositing. Enable it automatically if needed, otherwise force direct rendering
--use-root-window : Composite Overlay Window support was added to the server six years ago. We can drop this
--background-image : Use the wallpaper plugin
--no-detection : Use ccsm
Merge lp:~smspillaz/compiz-core/compiz-core.dropuseless-switches into lp:compiz-core