Webfonts don't load when running the dev server

Due to this bug: https://github.com/iamkun/dayjs/issues/792

* fix #1963 - Mentions are visually incorrect when used in message replies

And also allow the user to specify the JID to where the conversation has
moved to.

- Use :before to make sure container maintains its height
- Don't space out words in the textarea

- Always clear queue after fetching messages from cache
- Empty `message_queue` without waiting for all messages to first be processed.
- Don't assume that `this.messages` is set by the time `queueMessage` is called

Make sure dist dir is included in headless NPM package

* README: fix broken links

* fix references to tests.html

The file was moved in e7aed050

in @converse/headless instead of injecting HTML via the view