* Support for custom messages and redirects when creating posts
When a post/topic is created Discourse serializes a `NewPostResult`
object. Normally this contains a status like `created_post` or
errors describing why the post could not be created.
There are times when a plugin might want to take the inputted post
and do something in the background. In this case, the plugin
can return a custom `message` and `route_to` attribute in the
`NewPostResult`.
If present, the message will be displayed in an alert, and when "Ok" is
clicked the user will be routed to the new URL.
* Destroy the draft in parallel
