Redesign homepage

And another one!  Now with randomised crops and locatable seeds.

This is an incomplete version of the homepage redesign that I want to push up to our staging server so we can start to see how it looks "for real". It is lacking tests for all the homepage partials. Apart from that, the code has been reviewed/seen by about 4-5 people at this point. Still, it should have tests written and a more formal code review before it can officially be considered "delivered" let alone "accepted".