allow non-coding transcripts with CDS to be exported as GTF with CDS
allow non-coding transcripts with CDS to be exported as GTF with CDS

Primarily seen with Ensembl GTF where transcripts with biotype of
nonsense_mediated_decay will have CDS features, but were not being
exported as GTF with CDS intact. Now we blindly export all CDS without
checking transcript for protein coding status.

tjparnell/biotoolbox