* Refactor parts of BABE verification into separate module
* Fix silly compiler error
* Move more of the verification code to verification.rs
* Remove some unused imports
* Fix line width
* fix testsuite compile error
* Fix compile errors in tests
* Move authorship-related code to its own files
* fix compile errors in tests
* Respond to review comments by @rphmeier
* improve docs
* fix compile error
* Add missing doc comment