Fix custom title and avatar parsing in profiles.

Had messed up: centred avatar/title combos; and gang tags.
Fix parsing avatar from posts.

Some people have non-avatar images like gang tags.
Clean up custom title HTML.

Similar to posts HTML: remove &#13; encoded carriage returns and <b/>
day-ruining would-work-if-html-was-xml tags.
Fix parsing new Forums design.

Updated the changed fixtures, then made tests pass. Main issue was not parsing
the right page number of number of pages from a page of posts. Since the new
layout is "not set in stone" according to @Choochacacko, we'll keep the old
parsing code as a fallback.
Fix crash when a thread has no tag.

Don't bother searching for updated tags if we don't have one to search for.
Implement bookmarks parsing tests.

An empty test is not very helpful. Implementing the tests uncovered a thread
tag parsing bug.
Update thread list fixture and pass tests.