Update devtools
Add line coverage for forked block via intercepting fork
Prefer Kernel#fail over Kernel#raise
Add specs for Mutator::Registry and simplify it
Fix mutator registry use from specs
Remove dead code
Add specs and simplify Scope.wrap
Add specs for Mutation#insert
Reduce public interface ov Mutant::Env
Add specs for warning behavior on Class#name violations
Fix duplicate emit of neutral mutaiton on memoized instance methods
Add specs for Subject::Method::Instance#public?
Fix style

* Actually a hack to move an uncovered line togehter with a covered one.
* Will someone notice and complain?
* Is there a better idea?
Fix warning expectation specs
Reduce public interface of Subject
Add specs for Subject#tests
Prepare version 0.6.7
Correct miscellaneous typos

Mostly comments
Fix typo in readme
Switch to single quotes - no interpolation