Release Notes
- **Major change**: This release updates changes the API of the `DataFrameSchema` object.
Instead of passing a list of `Column`s, you now pass a dictionary where the keys are `column_name`s
values are `Column` objects. This makes the API feel a lot more familiar for pandas users, who may
often define `DataFrame`s in a similar way (see [README](https://github.com/cosmicBboy/pandera/blob/master/README.md) for details).
- renamed `Validator` to `Check` for brevity and clarity (accordingly renamed `validator_{input, output}`
to `check_{input, output}`.
- created convenience variables for `PandasDtype` so they can be accessed in `pandera` namespace:
`Bool`, `DatetTime`, `Category`, `Float`, `Int`, `Object`, `String`, `Timedelta`