generate 'fundec_cong' attribute for new-style (co)datatypes * * * compile

got rid of dynamic scoping the easy way

removed trivial 'rec' examples for nonrecursive types (I could also have added the 'old.' prefix in front of the constant names)

more liberal merging of BNFs and constructor sugar * * * make sure that the cache doesn't produce 'DUP's

se 'wrap_free_constructors' to register 'sum' , 'prod', 'unit', 'bool' with their discriminators/selectors * * * cleaner simp/iff sets

have the same no-update semantics for 'case' as for 'Ctr_Sugar' and BNF data (this might not be the final word on the matter, but using a consistent policy seems like a good idea)