The Perl process was exiting directly when called but that interfered with proper locking for the forked async process. Now Perl returns results to the C process which handles all errors, including signals.
Switch from Devel::Cover because it would not report on branch coverage for reports converted from gcov.
Branch coverage is not complete, so for the time being errors will only be generated when statement coverage is not complete. Coverage of unit tests is not displayed in the report unless they are incomplete for either statement or branch coverage.
* Replace remaining NDEBUG blocks with the more granular DEBUG_UNIT.
* Remove some debug memset() calls in MemContext since valgrind is more useful for these checks.
Move command begin to C except when it must be called after another command in Perl (e.g. expire after backup). Command begin logs correctly for complex data types like hash and list. Specify which commands will log to file immediately and set the default log level for log messages that are common to all commands. File logging is initiated from C.
* 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.
