Gaby Whitehead

Links to: https://github.com/ehn-dcc-development/ehn-dcc-schema/issues/112 Initially opened on ehn-dcc-schema but is an ehn-dcc-valuesets issue only, so we continue here.

Enhancement: I appreciate in a 2-file project it's probably not so much an issue but you really shouldn't be putting `using namespace std` in a header file as this forcibly...