Use "core" namespace internally

builtin/async/init.lua

builtin/common/async_event.lua

builtin/common/misc_helpers.lua

builtin/common/serialize.lua

builtin/game/auth.lua

builtin/game/chatcommands.lua

builtin/game/deprecated.lua

builtin/game/detached_inventory.lua

builtin/game/falling.lua

builtin/game/features.lua

builtin/game/forceloading.lua

builtin/game/item.lua

builtin/game/item_entity.lua

builtin/game/misc.lua

builtin/game/privileges.lua

builtin/game/register.lua

builtin/game/statbars.lua

builtin/game/static_spawn.lua

builtin/init.lua

builtin/mainmenu/init.lua