Delete unused #import.
Animate GIFs in post preview.
Shush Xcode.
"UIKit and Foundation" -> "Framework Categories".
Factor out synchronous version of -[ALAssetLibrary assetForURL:...]

Not entirely sure why there isn't a simple version of that method.
Don't crash in -[NSURL queryDictionary] when no equals signs are in the query string.
Clear back button on post previews.
Preview threads before posting.

* Extracted an "image attachment interpolator" that turns AwfulTextAttachments
  into [img] tags.
* Real hack job subclassing AwfulPostPreviewViewController.
* Augment AwfulThreadCell a bit so we can reuse it in the preview screen.