Fix registering buckets in foreign mod namespaces

Author: appgurueu

game_api.txt

@@ -35,6 +35,7 @@ The bucket API allows registering new types of buckets for non-default liquids.
 
 The filled bucket item is returned to the player that uses an empty bucket pointing to the given liquid source.
 When punching with an empty bucket pointing to an entity or a non-liquid node, the on_punch of the entity or node will be triggered.
+The bucket API also allows registering buckets in other namespace using colon-prefixed itemname (i.e. ":cows:bucket_milk").
 
 
 Beds API

mods/bucket/init.lua

@@ -51,6 +51,8 @@ end
 -- This function can be called from any mod (that depends on bucket).
 function bucket.register_liquid(source, flowing, itemname, inventory_image, name,
 		groups, force_renew)
+	local itemname_raw = itemname
+	itemname = itemname and itemname:match("^:(.+)") or itemname
 	bucket.liquids[source] = {
 		source = source,
 		flowing = flowing,
@@ -60,7 +62,7 @@ function bucket.register_liquid(source, flowing, itemname, inventory_image, name
 	bucket.liquids[flowing] = bucket.liquids[source]
 
 	if itemname ~= nil then
-		minetest.register_craftitem(itemname, {
+		minetest.register_craftitem(itemname_raw, {
 			description = name,
 			inventory_image = inventory_image,
 			stack_max = 1,