Pretty sure netherroot grows now

Rates still need to be tested, since I just bonemealed the hell outta
them...
Assorted farming functionality

Let's see... lotsa stuff :)

Plants are one-click break.
Vanilla bonemeal has been disabled on barley and netherroot.
Hoeing soulsand now damages the hoe and plays a sound.
Peat now has the same model and slowing effect as soulsand.
Weird behavior found: if you hoe soulsand that you're standing on, you
fall through as it changes to peat. You can jump out, but that shouldn't
happen.
Peat's texture is butt ugly. May change in the future.