Created by: mkszuba
Description
Port changes made to MGIParser ensembl-xref, including unit tests, back to ensembl:feature/xref_sprint.
Use case
See ENSCORESW-3215. Originally worked on by Prem.
Benefits
Salvage more work from the 2018 xref sprint.
Possible Drawbacks
Increased test-suite run time (note: Travis does not automatically execute tests from misc-scripts/xref_mapping yet).
Testing
Have you added/modified unit tests to test the changes?
Yes.
If so, do the tests pass/fail?
They pass.
Have you run the entire test suite and no regression was detected?
Yes (including tests from misc-scripts/xref_mapping), no regression detected.