This let's us populate the `from_real_jid` attribute for messages in
cases where the user's nickname has changed.
Only save the occupant-id if the MUC supports it
Store all advertised features on the `chatbox.features` model.
This allows us to look up a feature without using the async
`disco.supports` API.
Updates #2241
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
- Update to the latest @converse/skeletor (which uses mergebounce to batch writes)
- Flush storage before logging out
- Flush when reloading the tab
- Create initStorage method