Muons

Added information to full chain for the cosmic ray muon background using an approximation from IC86 Corsika files and Muon Gun weights
I have a conceptual question here: it seems you have _splines_ in `MuonGun`, that you evaluate to write out the `.d` file and then interpolate them again using _splines_. Can we not just use the original splines from `MuonGun` itself?