v0.6.1: Provide Python3 compatibility fixes from @TheOneHyer. Also in…

…clude in GFFParser and use six compatibility library for urllib issues. Fixes chapmanb#90

v0.6: Handle trans-splicing GFF cases where child locations may not m…

…atch back to parents. Fixes chapmanb#91

bcbio-gff v0.4

Version 0.6.0 release plus move into own bcbio-nextgen repository