- Add DOMParser and XMLSerializer (Lauri Rooden)
 - Add firstElementChild and lastElementChild (Lauri Rooden)
 - Add nextElementSibling and previousElementSibling (Lauri Rooden)

Removed Features:

 - Remove funding.yml (Lauri Rooden)

Fixes:

 - Fix Style Guide link (Lauri Rooden)
 - Fix inefficient regular expression (Lauri Rooden)
 - Fix travis test (Lauri Rooden)

Enhancements:

 - Add test for broken dom (Lauri Rooden)
 - Run CodeQL once a month (Lauri Rooden)
 - Use local @litejs/cli for tests (Lauri Rooden)
 - Improve parsing StyleMap (Lauri Rooden)
 - Accept optional `!` on comment end tag (Lauri Rooden)
 - Reduce times documentElement set (Lauri Rooden)
 - Use more specific regexp in camelCase (Lauri Rooden)
 - Use c8 for coverage (Lauri Rooden)
 - Update documentElement and body on documentElement change (Lauri Rooden)
 - Replace travis with github actions and litejs with @litejs/cli (Lauri Rooden)
 - Export DocumentFragment (Ferdinand Prantl)