Hierarchical posts

[Skud]

Currently posts have many comments. We would like to convert everything to be a post, but make each post have a parent or "in reply to" field which points to the post it's replying to.

This creates a hierarchy of discussion, allowing threaded discussions.

Post display should indent or otherwise show the reply hierarchy in a nice way.

When viewing any post, you should see all child posts (i.e. any replies to that post). If there is a parent post, there should be a link to it at the top of the page, but it shouldn't be displayed.

NOTE: this issue is copied from https://www.pivotaltracker.com/story/show/79656526 -- please update in both places during this hopefully short transition period!

[Skud]

Task breakdown (from PT):

• add parent_post property to post model - DONE
• display a post and all its children on one page - DONE
• link a post's parent (if it exists) at the top of that post's page - DONE
• display post replies with indentation or other styling to show reply threading - DONE
• show the post you're replying to
• move comment notifications to posts instead
• Redirect comments RSS to posts RSS
• write a rake task to convert all existing comments to posts
• (later, once it's bedded down) remove old comments views, routes, controllers, etc

[Skud]

Further work to do (should spawn a new story):

When replying to a post, we show you the post but then skip you down to an anchor tag to put you directly into the post reply form. The post itself is then kind of hidden, though you can scroll up to it. This is kind of icky UI-wise. It would be nice if, instead, we just showed a shortened portion of the post you're replying to (a paragraph or so), with a "Read more..." link that displays the rest. This is presumably a JS thing. We think we should break it out into a separate story because we were getting a bit bogged down in it.

[cesy]

This is important and keeps slipping, but we don't want to hold up Release 9 for it.