This allows to write
let k: Kurtosis = a.iter().collect();
instead of
let k: Kurtosis = a.iter().map(|x| *x).collect();
but breaks type inference for code like
let m: Min = (1..6).map(Into::into).collect();
where
let m: Min = (1..6).map(f64::from).collect();
has to be used instead.
Fixes#8.
