Parsuricata

Fixed
- Resolve minor typing incorrectness (`Option.settings` was referencing removed `KeyValue` type)

BREAKING
- Comma-separated settings now parsed as `Settings` tuple (previously, a `Literal` would be used, or parsing would fail, if some settings were quote-delimited strings) [GH15](https://github.com/theY4Kman/parsuricata/issues/15)

Added
- Support parsing of comma-delimited settings

Fixed
- Resolve parsing failures with reduced IPv6 addresses. [GH14](https://github.com/theY4Kman/parsuricata/issues/14)

Fixed
- Added missing MIT `LICENSE` file. [GH12](https://github.com/theY4Kman/parsuricata/issues/12)

Fixed
- Use correct version in `parsuricata.__version__`

Changed
- Improve performance of `Setting` class instantiation

Added
- _DOC:_ added CHANGELOG

Fixed
- Allow comments in rules files (e.g. ` Comment`)
- Allow any string for protocol (previously, a static list of protocols was used, but this list changes all the time)
- Allow numbers in option keywords (e.g. `asn1: double_overflow;`)
- Allow dashes in option keywords (e.g. `app-layer-event:applayer_mismatch_protocol_both_directions;`)
- Allow comma-delimited literals in option settings (e.g. `flowint:applayer.anomaly.count,+,1;`)
- Allow unescaped double quotes inside quoted strings, like Suricata allows (e.g. `pcre:"/^["']?post/Ri";`)
- Faithfully reproduce quoted strings and unquoted literals in option settings

Changed
- Changed minimum Python version to 3.6
- Upgraded lark-parser to 0.12.0
- _DEV:_ upgraded pytest to 6.2.5