(feat): @ DLKR's feature requests for blogs.

https://www.minds.com/newsfeed/945940525060898816

1. Keep the WYSIWYG editor, but let us purists use markdown
2. Let us use numbered and bullet-point lists
3. Let us insert horizontal lines. In Markdown, these are "---"
4. Make it easy to import posts from other platforms. Personally, I want to be able to import from Write.as and auto-insert a canonical link.