Function5.curried not implemented

The following code fails at runt-time:

```Scala
object Test extends App {
  val f = (x1: Int, x2: Int, x3: Int, x4: Int, x5: Int) => x1 + x2 + x3 + x4 + x5
  println(f.curried(1)(2)(3)(4)(5))
}
```

`curried` in Function5 up to Function22 are not implemented.