Kerbal Space Program

When writing a large number of tests, it's often useful to have an abstract superclass, particularly for e.g. PartModules where a lot of setup has to be done to get into a testable state. However, it looks like TestManager doesn't check whether UnitTest subclasses are abstract (or generic I think) before adding them, so instead it generates an exception.

Marking as very low because (1) I'm probably one of like three people who actually try to do any sort of unit testing in KSP mods, and (2) I may end up using my own test runner at some point