improved by using `memchr` to search for newlines][1.7m].
* [`f32::to_degrees` and `f32::to_radians` are stable][1.7f]. The
`f64` variants were stabilized previously.
-* [`BTreeMap` was rewritten to use less memory improve performance of
- insertion and iteration, the latter by as much as 5x`][1.7bm].
+* [`BTreeMap` was rewritten to use less memory and improve the performance
+ of insertion and iteration, the latter by as much as 5x`][1.7bm].
* [`BTreeSet` and its iterators, `Iter`, `IntoIter`, and `Range` are
covariant over their contained type][1.7bt].
* [`LinkedList` and its iterators, `Iter` and `IntoIter` are covariant