Fix clippy warnings
This MR was intended as a simple starting point to fix clippy warnings, and let me down a rabbit hole to implement things in orbclient, and then come back.
Most changes are minor (remove & in front of a reference) but I basically rewrote config.rs using Color's Deserialize, and serde - avoiding the intermediate TmpConfig, using serde defaults and Default::default.
Added some tests, but they are not running in CI yet, and I can't run them locally - so they need completing.
But I thought I'd share the MR as it is and see if looks OK to folks.