2.18.1 bugfix release * Identify SteamOS as an Arch Linux derivative. * Extend the list of supported native libraries for packages dependencies declarations. * archive_dependencies_check - Include archive extra parts during extraction dependencies check. * icons_inclusion - Fail explicitly if called with no argument and no applications list can be guessed. * launcher_write_script - Throw an explicit error if called with an empty argument. * print_instructions - Clear the list of unknown libraries after it has been displayed once.