Tests for ExtinctionProcessor

I have just written some tests for the ExtinctionProcessor. They all pass, so everything seems fine.

Also, I made the ExtinctionProcessor use the provided EntityFactory, instead of letting the class itself decide which one to use. This makes the class more flexible.
You should consider annotating the class with `@RunWith(MockitoJUnitRunner.class)` and then declaring the `private World world;` with the `@Mock` annotation. This provides a clearer testing structure, as it is immediately visible that a variable is actually a mock (it also saves lines in the setup method).