Pandabear

Feat

- 1) Add support for `Optional` columns in schema definitions. Add tests too. 2) Add custom errors when columns are missing and when schema definition is wrong. 3) Non-small refactor in model.py. Move colunm checks to top and simplify some things (more can be done though)

Fix

- Remove `regex` optional argument from `check` custom check decorator

Refactor

- Decreate nesting in _select_matching_names
- Refactor `_validate_multiindex` so it works like `_validate_columns` (also refactored a bit), and overall simplifies the code

Fix

- Do not coerce order when when Config.filter = True
- remove typo
- Cast df.index as series

Refactor

- StrictConfig not reused, move into schema

Fix

- Rename pandabear.typing -> pandebear.typehints

Refactor

- Clean up imports

Feat

- Implement custom check functionality in schema definitions

Refactor

- **tests**: Refactor tests to split test classes on success/failure and dataframe/series