Created a ReviewUIHook to allow extensions to register their
own ReviewUIs into ReviewBoard.
Manually tested with XMLReviewUIExtension: http://reviews.reviewboard.org/r/3564/
- Successfully installed this extension with its own ReviewUI
- Succcesfully registered XMLReviewUI through XMLReviewUIHook
- Once installed, able to review XML file attachments via the "Review" button
- Color markup for the XML file attachment correctly rendered through pygments
These will appear in API docs at some point, so this should be in sentence form, and we shouldn't use …