- when only a partial stacktrace is desirable.

ENH: add stack trace decorators

- the 0-th frame is always printStack(), so skip that and emit
  some headers/footers instead. Eg,

  [stack trace]
  =============
  #1  Foam::SymmTensor<double> Foam::inv<double>(...)
  #2  Foam::inv(Foam::UList<Foam::SymmTensor<double>> const&) ...
  ...
  =============