Follow-up from "Resolve "handling of off-shell particles""

The following discussion from !201 (merged) should be addressed:

• @rulrich started a discussion: (+3 comments)

  Hello @riehn

  here are a few questions:

  • why is the code limited to hadrons/nuclei? I understand this is the primary use-case, but should this not be handled in a more flexible way, or even left open? I can see why we don't care for photons, electrons, muons, etc. ... I am wondering what is your opinion.

  • please replace all "REQUIRE"s by "CHECK"s in the testOnShellCheck. The advantage is that CHECK will run all the other CHECKs, too, while REQUIRE will stop at the first failure.

  • in pythia/Decay.cc, what is the signficance of changing:

    • fPythia.readString("Check:particleData = 0");
    • fPythia.readString("Check:event = 1");

  What is the impact of the new module? Does it produce less failures/warning? Is it more robust now? Does the shower of vertical_eas change in a [meaningful] way?