Support markdown

[bummytime]

Currently, the new editor does not handle markdown very well. The web editor doesn't appear to allow the visual editing of markdown either, however it handles line endings much better. From a user:

Today I tried to edit a post that I had started on my laptop with the visual editor enabled.

When I click on the post within the iOS app I saw this:

Editing the post looks very similar. The problem here for me is that I don’t know where the line breaks are, so it becomes very hard to edit the post. Also, I’m hesitant to edit the post as it might break the whitespace.

Here is a preview of the post within the app:

Maybe if we detect the presence of markdown, we only allow the user to edit in HTML mode??