Correct method name
Cleanup namespace matcher
Remove useless comment
Use long operator form in non boolean context
Provide mutant specific metrics:mutant task
Fix code style in namespace matcher
Drastically simplify reporter public interface

The new one is simply: Mutant::Reporter#report(object)

Where object is one of:

Mutant::Subject
Mutant::Mutation
Mutant::Config
Mutant::Runner::Config (final and stats report)
Remove Mutant::Reporter::Stats

This mutable class was used to steer the control flow. The runner tree
will form the same stats with a far better level of detail.
Use new reporter interface in runner
Use word operator for control flow
Equalize CLI on generated config object