0.7.9.2:

0.7.9.2:
	Some PCL fixups (again, thanks to Pierre Mai and Gerd Moellmann)
	... make some DEFMETHOD/DEFGENERIC mismatches signal
		PROGRAM-ERROR
	... delete an apparently no-op "optimization"
	... comment from Gerd Moellmann on COMPUTE-EFFECTIVE-METHOD
		(arguably this should live in the user manual instead,
		when said document gains a section on the MOP)