__init__.py: split up importing standard modules
__init__.py: gettext module imported without being used
__init__.py: lazy import of pkg_resources
__init__.py: split up importing from pytz.lazy
__init__.py: LazyList and LazySet are not used
__init__.py: lazy import of pytz.tzinfo.unpickler
__init__.py: lazy import of pytz.tzfile.build_tzinfo, disable _byte_string which is not used