Change `window_size` to `[f64; 2]`
Change `window_size` to `[f64; 2]`

See https://github.com/PistonDevelopers/piston/issues/1254

- Changed `window_size` to `[f64; 2]`
- Removed `Eq` trait (because of `f64`)
- Removed `Hash` trait (because of `f64`)

bvssvni/viewport,PistonDevelopers/viewport