ReplayMachine can re-run an previous executed path..
The ReplayMachine takes a Profiler from a previous execution and will re-run that execution
in the same order. The edges and vertices will called exactly the same order.
If the last element of the execution is an edge, the ReplayMachine will execute the target
vertex as well.
A typical use case could be a test that encountered a failure, and now you
want to execute that test and see iff it can reproduce that failure.