Big updates to containers, inventories, and slots
* added SLOT_CLICK event, which triggers each time a player clicks an inventory slot
* added missing OPEN_INVENTORY events for EnderChest, StorageMinecart, and Beacon
* added Beacon with basic options for mods
** able to set any potion effect, including ones not normally supported by the Beacon (such as nightvision).
** able to check valid effects
* added SlotType to help define inventory slots, such as Inventory, Armor, Quickbar, Craft, Result, Outside of window, etc.
* added ability to update inventory slots, both individual, changed, and cursor
* added 4 OContainerXX classes in order to add "getInventory()" override methods
* added InventoryCrafting to help with inventories that contain crafting slots separate from result slots
* updated Anvil to be a subclass of InventoryCrafting to better use both crafting slots and result slots