rename all the Key* types, add missing "Mix"

Set	-> Set does Setty
Bag	-> Bag does Baggy
	-> Mix does Mixy
KeySet	-> SetHash does Setty does MixHash[Bool,False]
KeyBag	-> BagHash does Baggy does MixHash[Uint,0]
KeyHash	-> MixHash does Mixy  does MixHash[Real,0.0]