Yorm

- Fixed `YAMLLoadWarning` by using `yaml.safe_load()`.

- Updated `PyYAML` to `5.1` for security fixes.

- Added `Number` (and `NullableNumber`) type for floats that store as integers when possible.

- Fixed the `List` converter to accept tuples as lists.

- Implemented `match` utility (credit: [astronouth7303](https://github.com/astronouth7303)).
- Including file contents in parse exceptions.
- Added sync parameter `auto_resolve` to clean up file conflicts automatically.

- Removed warnings about calling save/load unnecessarily.
- Now allowing keyword arguments to be passed to class construction via `create` and `find` utilities.
- Now adding additional attributes from `__init__` on `AttributeDictionary`.
- NOTE: For this feature to work, `__init__` must not use positional arguments.
- **DEPRECIATION**: Renamed `ModelMixin.new` to `ModelMixin.create`.