Added standard InChi key & string for Methane
Added standard InChi key & string for Methane

Values obtained from: https://pubchem.ncbi.nlm.nih.gov/compound/297#section=Names-and-Identifiers
CoolProp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp