transcription of code from original C source base.
Bug fix to GEDCOMBase#xref_check, which didn't qualify index lookup when printing an error message.
Added Transmission#self_check, which calls new FamilyRecord.self_check and IndividualRecord.self_check Checks the gedcom file FAMC, FAMS, HUSB, WIFE, CHIL and SUBM xrefs resolve to valid records. Required adding IndividualRecord.child? and IndividualRecord.spouse? for tests. Fixed bug in IndividualRecord.spouses and IndividualRecord.parents_family as neither worked and were used by tests.
Removed 'require chart.rb' which was left in production code by mistake
Added in the GEDCOM 5.5.1 Draft changes. Most changes are alternatives to the 5.5 standard, but the Multimedia record File and Format structure is different, so these are now classes, rather than attributes.