Add support for updated MHD transactions (v4.0.2)

[ohr]

This set of updates has breaking changes as outlined in https://profiles.ihe.net/ITI/MHD/a_issues.html, particularly DocumentManifest has been replaced by List.

Look for a concept of differentiating between old and new MHD versions. Production systems might need to support both at the same time and select one in favor of the other.