Plant from wishlist

[Skud]

From any wishlist item, I should be able to click something to say "plant now", and once that's done, it gets marked as "Done" with today's date. It would also be nice to link wishlists/plantings, much as we want to link plantings/harvests (#501).

For inspiration: this is a bit like when you say "cast on" from your queue in Ravelry.