BREAKING CHANGE: The signature for an `ItemCtor` has changed. The second parameter is now a type extending `Strongbox` instead of a `container` string. This allows for deeper integration between a custom `Item` implementation and a custom `Strongbox` implementation. Further, a custom `container` now must be an absolute path after it's been slugified.
- The `Strongbox.clearAll()` method now accepts a `force` param which, if `true`, will rimraf the entire container.
- Added two methods to the `Strongbox` class which can be overridden to accept custom options, apply defaults to those options, then validate and/or transform them.
- Added nearly-complete unit test coverage and added E2E coverage of the `BaseItem` implementation.
Christopher Hiller