inserted some "addsimps [subset_empty]"; also tidied (a lot)
inserted some "addsimps [subset_empty]"; also tidied (a lot)

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle