interface decay routines in Epos

for Sibyll an interface for both generation of interactions and the particle decays is implemented. This allows for the treatment of 'internal' model decays within C8. This way the internal consistency of the models can be preserved (the interaction models are usually tuned to accelerator measurements of protons, pions and kaons using the internal decays to have everything more short lived than a K_s decay) while still exposing the heritage of the particles in C8. This would also be most similar to the configuration in C7.
In the very least a comparison between 'internal' decays and always using pythia decays should be done.

This requires the decay routines in Epos to be exposed. Qgsjet does not have resonances (or in other words internal decays are hard coded).