Function ellipsis 

pub fn ellipsis<'a, S: Into<Cow<'a, str>>>(input: S) -> Cow<'a, str>

Replace ellipsis (…) with the appropriate unicode character

Example

use crowbook_text_processing::clean;
let s = clean::ellipsis("foo...");
assert_eq!(&s, "foo…");
let s = clean::ellipsis("foo. . . ");
assert_eq!(&s, "foo.\u{a0}.\u{a0}. "); // non breaking spaces