clean up some proofs; add lemmas spair_strict_iff, spair_less_iff, spair_eq_iff; add instance for class bifinite
clean up some proofs;
add lemmas spair_strict_iff, spair_less_iff, spair_eq_iff;
add instance for class bifinite

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