Moving `public/images` dir to `assets/images`, because it conflicts with gitlab CI/CD for documentation.
Moving `assets/styles.css` to `assets/styles/styles.css`.
Related to #117.
* Builtin Prosody, Share chat url: option to have a transparent background (for streaming integration).
* Builtin Prosody, Share chat url: fixed new day hidding when no scrollbar in readonly mode.
Modal for video owner (and instance's moderators) that allows to generate a link to the chat. So you can - for example - obtain the url to use for OBS integration.
WIP
* All buttons are in the same DOM container as the iframe
* Icons for buttons
* Rewriting the build process
* Simplier state management
* Buttons are hidden using CSS
