Optimize PitMP execution by excluding detected mutations

[oscarlvp]

Right now PitMP may analyze the same mutation several times if it is covered by tests in different modules. So, before running the tests on a module it would be nice to check if the mutation was detected before by the tests of a previous module. One way to do it could be to create a listener that records the outcome for each mutation and then an interceptor that prevents killed mutants from being analyzed later.

[oscarlvp]

Another alternative to explore is to implement a test prioritizer. This type of plugin can assign tests to a mutant and alter the order in which they are run.

[nrainer]

To some degree addressed by a side-effect of the fix for #19.