A start on improving the events page

This change merely changes the behaviour of /events to show the hot events rather than a list sorted by date. The latter can be better served another way. I've also added a search box... for those search addicts among us

This is all part of a bigger masterplan. I hope to introduce a calendar type view to replace the "latest events" that I've removed, and a "My events" pages in the near future for those logged in

And I will soon fix the fact that we pretty much duplicate the front page (I need to think some more about the frontpage). But, I think I should incrementally make changes as to gather feedback from others