61 Images

Package image defines the Image interface:

```
package image

type Image interface {
	ColorModel() color.Model
	Bounds() Rectangle
	At(x, y int) color.Color
}
```

(See the documentation for all the details.)

Also, color.Color and color.Model are interfaces, but we'll ignore that
by using the predefined implementations color.RGBA and color.RGBAModel.
These interfaces and types are specified by the image/color package
62 Exercise: Images
62 Exercise: Images - done
63 Exercise: Rot13 Reader
63 Exercise: ROT13 Reader - done