### Bug fixes

Fix an issue where the dots past the wrapping point were displayed incorrectly when using `highlightWhitespace` with a wrapped sequence of spaces.

Improve performance of documents displaying lots of highlighted spaces by using a CSS background instead of pseudo-element.

### New features

`placeholder` now allows a function that constructs the placedholder DOM to be passed in, and uses `cloneNode` when a raw element is passed in, to prevent adding the same element to multiple editors.