Add a rich text editor

Maybe use ProseMirror to build one? It supports both rich text and Markdown, and collaborative editing. Here Atlassian has published an open source editor built on ProseMirror: http://atlaskit.atlassian.com/packages/editor/editor-core (found out about that via Reddit).

Background: Talkyard is supposed to be simple to use also for non-tech people, e.g. people in small non-profits or local community neighborhood organizations or a small business in a developing country that runs its Q&A site from a smartphone. Maybe good if they won't need to wonder about what Markdown things like ** and ### means when looking at the smartphone screen, without seeing the preview (because screen too small).

Update 2019-12: Now there's ReMirror, an editor built on ProseMirror — maybe it's easy to use? https://github.com/ifiokjr/remirror

Update 2020-07 There's also Rich-markdown-editor, https://github.com/outline/rich-markdown-editor, build on ProseMirror and React.js.