My first idea was to make the footer bigger and add each onion link in it, but since the onion addresses are in a file signed with gpg, I thought I'd just add a link to the Tor page in the footer, so it would make it easier for people to find the onion url.

Fix #675

EDIT: that being said, if we can find a way to put the addresses directly in the footer without compromise on the security, it'd be cool to do so in the future.