[formats] Make gff.uniq() compatible with Python 3 (#273)
[formats] Make gff.uniq() compatible with Python 3 (#273)

* [formats] Make gff.uniq() compatible with py3

* [formats] Simplify ids addition in gff.uniq()

* [formats] No need to compute the score in gff.uniq()
tanghaibao/jcvi