Yaralyzer

* Bump `yara-python` to 4.3.0+ and deal with backwards incompatibility

* Lock `yara-python` at 4.2.3 bc 4.3.x causes problems

* Fix PyPi screenshots
* Raise better error message if yara rules file doesn't exist

* Fix PyPi screenshots

* All command lines args configurable via environment variables or `.yaralyzer` file
* Improve decoding attempt statistics tracking
* Add suppression notices
* Expose `--min-chardet-table-confidence` option

* Add `--log-level` option
* `BytesMatch.is_decodable()` method