Remove or replace footer quick links

None of the quick links in the footer correspond to actual pages in the site. The links should be replaced with actually useful links or removed.

Think I was discussing this with Oliver before, and yeah none of the quick links are useful. I can't really think of other important links so I'm probably going to remove them and just center the explore links, and I'll also add the itch.io social icon button because we now have an itch account.