Attmap

Fixed
- Made compatibile with setuptools 58 by removing use_2to3

Added
- `_excl_classes_from_todict`, which can be used to list classes to be excluded from the `dict` representation

Fixed
- A bug that caused double-backslashes

Added
- block style YAML representation support for lists
- recursive value expansion in `PathExAttMap`

Added
- distribute license with the package

Added
- license file

Added
- New feature to allow not printing the object type on reprs.