Remove the /ip_addresses page. This page allowed moderators to search
users by IP, and to see recent activity tied to an IP. However, it was
limited to IPs tied to uploads, comments, dmails, artist edits, note
edits, and wiki edits.
Remove this page because it was limited in scope and because there are
better ways of doing what it did. The /user_events page is better at
catching sockpuppets because it tracks IPs for every login, not just for
certain types of edits. And the /user_actions page is better at
monitoring user activity because it shows all activity associated with
an account, not just for certain types of edits.
Removing this allows us to drop IP addresses from all tables besides the
user_events table. This is good because these IPs are no longer necessary
for any purpose, and because storing them forever is a liability.
Add a new IP address search page at /ip_addresses. Replaces the old
search page at /moderator/ip_addrs.
On user profile pages, show the user's last known IP to mods. Also add
search links for finding other IPs or accounts associated with the user.
IP address search uses a big UNION ALL statement to merge IP addresses
across various tables into a single view. This makes searching easier,
but is known to timeout in certain cases.
Fixes#4207 (the new IP search page supports searching by subnet).
