Add more bonemeal configuration options * Add bonemealEffectiveness: Multiplier on the effectiveness of bonemeal; the smaller this is, the more often bonemeal will fail to create growth. Set to 0 to disable bonemeal completely. * Add modifyBonemealGrowth: Reduces the amount of growth from a successful bonemeal on certain plants (uses IguanaMan's opinionated values) * Change difficultyScalingBoneMeal to require modifyBonemealGrowth and not disable bone mealing on hard (bonemealEffectiveness should be used instead) * Closes #71