I searched and replaced all molecular_weight and replaced them with molecular_mass
updating comments
updating comments and adding back liscense.txt
fixed more incorrect usages of name molecular weight
Add nds fission product yield to nuc_data
Add basic docs to ndsfpy
fixup wimsdfpy doc strings
Add errors to data and split getting and parsing
Add API for NDS data

Add NDS data to the fpyield c++ api and update python api accordingly.
Add NDS error data to API
Added amalgamation script
C++ file now alamation compliant.
extra types goes before h5wrap
Fix import ordering in ndsfpy
Add source citation
refactor *_yield to yield_*
Fix compilation issues
Added nuc listing method to mcnp Xsdir
Fix cython API
fix ndsfpy.py import issues