Atmospheric Sample Splines

[dbarrow257]

Right now, new atmospheric samples are explicitly coded to not handled splines:

MaCh3_DUNE/samplePDFDUNE/samplePDFDUNEAtm.cpp

Line 25 in ee09636

void samplePDFDUNEAtm::SetupSplines() {

Will need to address this going forward