simplified (and clarified) integration with Pure/ContextRules; removed "extra" rules as separate slots, only keep xtra_netpair for   single-step view of plain haz/safe rules;
simplified (and clarified) integration with Pure/ContextRules;
removed "extra" rules as separate slots, only keep xtra_netpair for
  single-step view of plain haz/safe rules;

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