This fixes about 130 clippy lints. Let me know if i should split up the commit.
I wasn't sure about some of the changes, especially map_or instead of map(...).unwrap_or(...) and if let instead of single arm match were not always a strict improvement in my opinion, but i'll leave that decision to the reviewer :)
There are about 150 lints left which i thought were clippy bugs or i didn't know how to fix.
cc @Manishearth
Source-Repo: https://github.com/servo/servo
Source-Revision: 9da739acefc7d1776bf727c8bf782eb79f241028
Updated string_cache to 0.2, and updated the dependencies that depend on string_cache.
Removed references to string_cache_plugin.
Import atom! and ns! from string_cache.
Replaced ns!("") by ns!().
Replaced ns!(XML) and co by ns!(xml) and co.
Replaced Atom::from_slice by Atom::from.
Replaced atom.as_slice() by &*atom.
r? @SimonSapin
Source-Repo: https://github.com/servo/servo
Source-Revision: 188fa9378c103093f1f8dac24bff0d9d237fd2bc
