Updated PDF example and 'good_test' to reflect changes
Modified makefile to include LHAPDF stuff
Added 'pdfSetPath' to override the PDF set path in the steering file
src/SPXPDF.cxx
Created SPXLHAPDF.h which outlines the LHAPDF fortran stuff
(Partially) fixed SPXPDF.cxx... added patch for std::to_string, syntax stuff