Change 'file://' URIs into 'file:'.

Add special source 'IMGT/LIGM_DB' (assumed to exist by SegmentParser,
but not explicitly connected with any species).

Collapse lists of data URIs by means of FTP file name globbing,
especially for the various RefSeq sources.

Updated some URIs to point to new data (e.g. FlyBase for Drosophila).