Registration Functions
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placeable_buckets.register(name, def)
	--Turn an existing bucket into a fillable bucket.
	--Currently, this function does assume that a craftitem version of the bucket already exists.
	--Inherits from minetest.register_node

	_replace = "modename:itemname",
	--The original name of the bucket, which will be replaced and aliased.

	description = "Description",

	_texture_base = "texture",
	--The name of the set of textures that this bucket will use, which should specifically be a .png file.
	--There should be 10 of these in total. In the textures folder, these textures would actually be "texture_1.png", "texture_2.png", etc.
	--Omit the ending underscore, number, and .png

	_groupname = "group",
	--A copy of this node is created for every visually distinct fill level.
	--To group these nodes togeter, this group name is required.

	_register_per_level = function(level)
	--This allows you to specify definition differences based on each fill level.

	_on_fill = function(pos, level)
	--Any time the bucket is filled, this function should be called.
	--This includes occasions where the fill level is incremented by a fraction, and the bucket doens't visually change.
