Unsorted extern-crate/use/mod/… statements

[regexident]

In addition (or as alternative) to https://github.com/Manishearth/rust-clippy/issues/880 I'd love to have a lint that warns on mal-sorted use statements inside a group.

So that this would trigger a warning:

use lorem::ipsum::{dolor, sit, amet};
use consectetur;
use adipiscing::elit;

while this wouldn't:

use adipiscing::elit;
use consectetur;
use lorem::ipsum::{amet, dolor, sit};

This is would probably be a candidate for pedantic.

[llogiq]

Again, this is very opinionated and probably more suited to rustfmt.

[regexident]

Fair point. And there appears to be an issue for it already: rust-lang/rustfmt#298.