Extra Genbank parser methods to aid RefSeqGPFFParser
Created by: tgrego
Xref RefSeqGPFFParser does the parsing of Genbank files. Refactoring this Xref parser as part of the xref sprint efforts led to the decision of using an existing genbank parser rather than implementing it again within the RefSeqGPFFParser.
This will obviously be better in terms of future maintainability, and if development efforts are concentrated in one place it will be more efficient.
Some required data was however not very easy to access using the Genbank parser, so this brings new methods that extract that data in an easy way.
No existing functionality has been modified, only new one added. Tests are included for the new methods.