* More optimized container suite that greatly improves build time.
* Added static Debian packages for Devel::Cover to reduce build time.
* Add deprecated state for containers. Deprecated containers may only be used to build packages.
* Remove Debian 8 from CI because it does not provide additional coverage over Ubuntu 14.04 and Ubuntu 16.04.
Refactor storage layer to allow for new repository filesystems using drivers. (Reviewed by Cynthia Shang.)
Refactor IO layer to allow for new compression formats, checksum types, and other capabilities using filters. (Reviewed by Cynthia Shang.)
* Full coverage is verified when specified.
* Modules marked with partial coverage will error if they are actually fully covered.
* Simplified test representation is DefineTest.
* Added new representation for queries in DefineTest and added API functions.
* Update modules using DefineTest to use new API.