Add a "Vec.sorted()" function

[matklad]

Yes, I still think this is a good idea:

Pre-RFC-ish: add Vec::sorted and friends

Hi! What do folks think about adding impl Vec<T> { fn sorted(self) -> Vec<T> where T: Ord { let mut this = self; this.sort(); this } // and seven other `sort` flavors? } to the stdlib? This method would allow to replace let mut deps_metadata = cx.dep_targets(unit) .iter() .map(|dep| metadata_of(dep, cx, metas)) .collect::<Vec<_>>(); deps_metadata.sort(); with a more fluent version: let deps_metadata = cx.dep_targets(unit) .iter() .m…