Derive `Clone` on `BuildFromWindowSettings`
Derive `Clone` on `BuildFromWindowSettings`

Changed `settings: WindowSettings` to `settings: &WindowSettings` for
making it easier to create multiple windows at once.

Closes https://github.com/PistonDevelopers/piston/issues/1072

bvssvni/piston,getynge/piston,PistonDevelopers/piston,bvssvni/piston,oldmanmike/piston,PistonDevelopers/piston