- Notes on the new attack group displays:
  * We want to group runs into consistent protocol runs.
  * Minimal req. for protocol run: equal \rho.
  * If two runs are candidates for a role in a protocol run,
    use a metric based on order and data. Maybe data is more important:
    if equal data, than order might be irrelevant.
  * Maybe we should refactor the xmlOut code first. In an extreme case,
    we first factor out all logic, and ranking, and grouping, in to a
    prepareAttackOutput structure; with a separate source file. Later we
    can convert this to either ASCII or DOT or XML or something.
    Now that I think of it; XML should be a plain state probably, and we
    could add a switch to also output more detailed attack things (is
    that relevant?)
- Add --filter-claim and --filter-label switches; parse as symbols, and
  turn into (global?) terms, add to switches termlists. Later check them
  using two new term functions:
  const char *termSymbolString(Term t);
  int termSymbolEqual(Term t1, Term t2);
  Iteration through the termlist should be done by hand.
- Maybe add warning for type of matching in the output, maybe stderr.
- SConstruct file should check whether ctags actually exists (avoiding
  errors)
- Proof output should be XML, with an external converter to dot format.
- Internal hash over input files (maybe after parsing?) and switch
  structure. This would make a caching mechanism much easier.