Ldap-filter

Change Log

- Fixes issue when parsing query strings that have `!` as part of an attribute value. Issue 7

Change Log

- Fixes bug where `None` was improperly returned for certain `NOT` filters.
- Migrates project to use `pyproject.toml` instead of `setup.py`.
- Project now marked as stable.

New Features

- New parser for LDAP filters
- Soundex library for approximate filter matching
- Unit tests for most of the existing code base.

This is the first pip release of the library.