Create ArmorJacket interface. Adjust MegaPlayer to make use of an
ArmorJacket affecting damage received. Implement ArmorJacket as
NormalJacket, FlakJacket, KevlarJacket and KevlarOmegaJacket. Create
KevlarOmegaArmorCheat to enable/toggle KevlarOmegaJacket. Add
KevlarOmegaArmorCheat to GameCheatListener in SeeteufelScreen.