Release version 0.2.0

* add `format()` and `format_iterate()` to support formatting strings in
  standard Python syntax, but with a datapath for fields.
* slightly update return type of `iterate()`

Release version 0.1.2

* A `SplitPath` is now a tuple of `_PathPart` objects, this changes the
  return type of `split()`
* `iterate()` now throws a `ValidationError` when there is a mismatch
  between the path part type and the collection type where previously it
  threw an `InvalidIterationError`; this is now consistent with all
  other functions.

Release version 0.1.1

* Fix: support ranges for `join()`

Release initial version 0.1.0