Changes

SPIGOT-5766: Updates related to the villager trading changes introduced in MC 1.14.

* The VillagerReplenishTradeEvent is now called whenever a villager restocks one of its trades. Previously, it was called in some (but not all) cases in which a villager updates the special price values of its merchant recipes.
* VillagerReplenishTradeEvent#get/setBonus have been deprecated and #setBonus has no effect anymore. The way villagers restock their trades has changed in MC 1.14: Instead of adjusting the max uses of their trades, they reset their uses to 0. #getBonus returns the value of MerchantRecipe#getUses now.
* Updated various outdated and inaccurate javadoc in MerchantRecipe.