Peprock

Feat

- **itertools**: implement `min_and_max()`
- **typing**: implement `typing` package
- **models**: improve type handling in `MetricPrefix.to()` and `MetricPrefix.convert()`

Fix

- **models**: add `__all__` to `metrix_prefix.py`

Refactor

- **typing**: retire `typing`
- **itertools**: retire `itertools`
- **models**: simplify type annotations
- **subclasses**: leverage `peprock.typing.T_co`
- **models**: extract base into constant

Perf

- **models**: remove cache from `MetricPrefix.to()`

Fix

- **models**: add missing py.typed marker

Feat

- **models**: implement `peprock.models.MetricPrefix`

Refactor

- turn peprock into namespace package

Feat

- **datetime**: implement constants `peprock.datetime.ONE_MICROSECOND`, `peprock.datetime.ONE_MILLISECOND`, `peprock.datetime.ONE_SECOND`, `peprock.datetime.ONE_MINUTE`, `peprock.datetime.ONE_HOUR`, `peprock.datetime.ONE_DAY`, `peprock.datetime.ONE_WEEK`
- **datetime**: implement `peprock.datetime.ensure_aware()`
- **datetime**: implement `peprock.datetime.is_naive()` and `peprock.datetime.is_aware()`