- makeTranscriptDbFromUCSC() - Address the CDS non-completeness issue.
  The status of the CDS (complete or not) can be inferred from the
  cds*Stat field (when present) of the UCSC table.

- makeTranscriptDbFromBiomart() - Add support for chromosome lengths.

- makeTranscriptDbFromGFF3() - Primary target: GFF3 files on the TAIR,
  Flybase and Wormbase websites/FTP servers.

