added the missing freshness-lemmas for nat, int, char and string and also the lemma for permutation acting on if's
added the missing freshness-lemmas for nat, int, char and string and
also the lemma for permutation acting on if's

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