Load second page instead of 'reaching the end' if all posts from first page were filtered out

[Sjmarf]

I've read all of the posts on the first page of mlemapp sorting by hot. If I enable 'hide read', I get 'no posts to be found'. It should instead keep loading more pages until it finds a page with unread items. Maybe there should be a limit to this though, incase something goes wrong and the API gets spammed?