Improve unread highlighting

[Throne3d]

There have been some suggestions made for how to improve the unread highlighting UI, and to make it more generally useful:

• A colored bar could be used above the unread reply to mark where you last read up to
• When clicking a deep link, the colored bar could show near the top of the page, indicating that you're past your previous unread link; it would permit you to click something to undo the action (or alternatively it could default "not read" and permit you to click something to move your unread point to this new place) – see Restore unread #82
• It may also be nifty to have this colored bar be a colored border on individual replies (left or right?) when they're unread; it may also appear on read replies to keep the layout around the border consistent
• This colored bar could shift when someone presses "Mark Unread Here", and the request could be sent using AJAX instead, which would unify the UI better
• Related to Notifications when posts are updated #6, this colored bar could appear at the end of a page once you've read it, and then when notified of new replies, these could be (optionally, toggleably) added to the end of the display, and marked as being distinct with the same colored bar which can be dismissed to indicate the new replies have been read
• If linked with the Specify if a post is tagged or not #32 it could be used to notify the user of new tags, update the UI without reloading with the new replies, and allow them to directly enter a reply

In the above, where the term "colored" is used, this should be considered an unobtrusive layout-dependent indicator, likely toggleable, which stands out from the rest of the replies as a UI element allowing you more control over your read point.