+ Adjust parsing of Dbxref to account for multiple values per DBTAG + Allow gff.load() of single level GFF3 feature (parent=mRNA, child=mRNA)
+ Adjust parsing of Dbxref to account for multiple values per DBTAG
+ Allow gff.load() of single level GFF3 feature (parent=mRNA, child=mRNA)

tanghaibao/jcvi,sgordon007/jcvi_062915