* remove unnecessary hashes around raw string literals
* remove unncessary literal `unwrap()`s
* remove panicking `unwrap()`
* remove unnecessary `unwrap()`
* use `[]` instead of `vec![]` where applicable
* remove (more) unnecessary explicit `into_iter()` calls
* remove redundant pattern matching
* don't cast to same type and constness
* do not `cfg(any(...` a single item
* remove needless pass by `&mut`
* prefer `or_default()` to `or_insert_with(T::default())`
* `filter_map()` better written as `filter()`
* incorrect `PartialOrd` impl on `Ord` type
* replace "slow zero-filled `Vec` initializations"
* remove redundant local bindings
* add required lifetime to associated constant