Fixed dead npc shopkeepers using the wrong loot panel, a symptom of them not using the correct corpse prefab
Involved moving CreateCorpse override up a level from HumanNPC to NPCPlayer, this turned into a bit of a refactor as I cleaned up the copy+pasted CreateCorpse methods in FrankensteinPet, ScarecrowNPC and GingerbreadNPC, exposed any differences in their corpse generation process as virtual properties (see CorpsePath, ShouldCorpseTakeChildren, KeepCorpseClothingIntact, OverrideCorpseName, ApplyLoot, CopyInventoryToCorpse)