Timeline feature

Proposed new feature:

• A timeline would allow content editors to create a basic timeline for sharing sequential information.
• Nedjo and I have been prototyping this for an Agaric project. This is based on the timeline extension provided by Bulma using two new paragraph types.
• It has been drafted to also use the methodology we sketched in for creating features on top of existing Drutopia features. In this case it adds a new field to Drutopia Page so that a page can contain a timeline.
• To do so requires both a new Drutopia Timeline feature as well as a new Drutopia Page Timeline feature. This allows us to not need a new content type but is definitely less intuitive in terms of building (and I'm not sure about using).
• To use a Bulma extension we'll need to compile the CSS meaning we'll need to move away from using Bulmaswatch.