Add tab index to listing links.

This makes it slightly easier to browse listings by keyword.
Add backend for new gold feature: "remember my visits".

Store and mark what links users have already read, even between
computers.
Add frontend for new gold feature: "remember my visits".
routing: Remove route for /doquery.

This should have gone in 5f916f5812e7c3920d0cb968470280d1198e1fff.
Remove obsolete selfserviceoatmeal.html
r.ui.Bubble: Don't position a Bubble off screen.
Show IDN on domain listings when appropriate.
Add anchor-top-left class for idn-help bubble.
POST_store_visits: Add VModhash requirement.
Feedback page update