AO3 Additions by williammmm

Currently adds:
- History tracking
- History Statistics
- Tag Blocking
- Highlights already-read works on search

Usage
- Works can be marked/unmarked as read by clicking the "(un)Mark as Read" button on the work page. (Has the extension icon next to it)
- The history page can be accessed by clicking the extension icon and then clicking "History"
- Same for the options page and the stats page
- Tags can be blocked by clicking the "Block Tag" button on the tag page, or by adding them to the list in the options page.