Fix image contraction scrolling bugs.
Fix DOM location of hovered images.
not needed
Optimize new Unread code.
Refactor adding of unread posts.
Unread.postsQuotingYou -> ECMAScript 6 Set
Overhaul quote threading.

- Separate post order data from read/unread status.
- Make compatible with unread line and scroll to last read post.
- Implement [Thread New Posts] link.
Release 4chan X v1.9.14.0.