Feature: Support parsing authority and additional records from DNS response. (#123 by @clue)

Feature: Support dumping records as part of outgoing binary DNS message. (#124 by @clue)

Feature: Forward compatibility with upcoming Cache v0.6 and Cache v1.0 (#121 by @clue)

Improve test suite to add forward compatibility with PHPUnit 7, test against PHP 7.3 and use legacy PHPUnit 5 on legacy HHVM. (#122 by @clue)