Use minetest instead of core namespace, discourage via luacheck

mods/bones/init.lua

@@ -149,7 +149,7 @@ local function may_replace(pos, player)
 end
 
 local drop = function(pos, itemstack)
-	local obj = core.add_item(pos, itemstack:take_item(itemstack:get_count()))
+	local obj = minetest.add_item(pos, itemstack:take_item(itemstack:get_count()))
 	if obj then
 		obj:setvelocity({
 			x = math.random(-10, 10) / 9,

mods/bucket/init.lua

@@ -141,7 +141,7 @@ minetest.register_craftitem("bucket:bucket_empty", {
 				else
 					local pos = user:getpos()
 					pos.y = math.floor(pos.y + 0.5)
-					core.add_item(pos, liquiddef.itemname)
+					minetest.add_item(pos, liquiddef.itemname)
 				end
 
 				-- set to return empty buckets minus 1

mods/doors/init.lua

@@ -185,7 +185,7 @@ end
 local function on_place_node(place_to, newnode,
 	placer, oldnode, itemstack, pointed_thing)
 	-- Run script hook
-	for _, callback in ipairs(core.registered_on_placenodes) do
+	for _, callback in ipairs(minetest.registered_on_placenodes) do
 		-- Deepcopy pos, node and pointed_thing because callback can modify them
 		local place_to_copy = {x = place_to.x, y = place_to.y, z = place_to.z}
 		local newnode_copy =