Added
- Abstract base parser as a contract for concrete file format parser implementations.
- Exposed `ConfigFile`, `BaseParser`, and `ParsingError` to the Public API. The base
parser is exposed to allow future custom extensions of the config file and what it
can parse by its users.
- `has_section` and `has_key` is now changed to a single `has` method which determines
whether you're checking a section or key by the presence of a dot.
- `IniParser` to support the ini format. It uses configparser internally, but it is
only exposed through the `ConfigFile` object.