- Modernize the `RegisterPanel` component and turn it into a Lit element.
- Improve CSS and move into plugin.
- Fix button click handler not being registered.
- Fix switching between login/register form after logging out (Fixes#1556)
Had to make various other changes due to incompatibilities.
- Use the new `lit` package instead of `lit-html` or `lit-element`
- Drop `haunted` since it breaks the rules by specifying `type: module`
but then doesn't import with file extensions
- Use Sass Dart instead of node-sass (fixes#2445)
- Upgrade Karma
