[WIP] Detect EDM schema versions during reading and ensure consistency

[tmadlener]

BEGINRELEASENOTES

• Detect the schema version of EDMs from the environment and compare them to the ones available from file to ensure that files can actually be read.
  • Avoid trying to read files for which the EDM version in the environment is too new

ENDRELEASENOTES

• Fixes Investigate whether it is possible to catch mismatched EDM versions early #848

This is some work that I had actually done a few months back and rediscovered now due to the discussion in #848. I am not entirely sure whether it's complete at this point.