Added conversion traits in `WindowSettings::new`
Added conversion traits in `WindowSettings::new`

Closes https://github.com/PistonDevelopers/window/issues/27

tempbottle/piston,mitchmindtree/piston,bvssvni/piston,PistonDevelopers/piston,getynge/piston,KevinFrans3/piston,caldwell/piston,oldmanmike/piston,axelmagn/piston,bvssvni/piston,placrosse/piston,bvssvni/window,Potpourri/piston,PistonDevelopers/piston,PistonDevelopers/window