Added proxy support (fixes #114). Thanks @Johni0702!

Proxies such as BungeeCord have the option to forward the real address,
UUID, and properties from the auth process to the backing server so that
they can appear to be in online mode even if they are not.
Add bonemeal interaction with saplings
Work something much more generic
Extend BlockPumpkinStem, BlockMelonStem and BlockTallGrass from BlockGrowable
Change to IBlockGrowable, add BlockGrass
Add BlockDoublePlant, modify BlockTallGrass
Add BlockPlant, BlockCrops and BlockDeadBush
Add ItemHoe
Add ItemSeeds, BlockStem, modify BlockCrops and remove BlockPumpkinStem, BlockMelonStem
Add ItemFoodSeeds, ItemFood and BlockCarrot, BlockPotato
Add ripe() method to BlockStem
Add BlockMushroom and huge mushrooms generation
spawn some green villager particles (needs isFertilizable() filtering)
Add BlockCocoa and BlockPumkin, add cocoa beans interaction
Add isFertilizable() and canGrowWithChance() methods to IBlockGrowable, and implementations