Added some attribs that were used in databases but not in this file. More to come. Plus general tidying up

Added optional passing of list of arrays to slice->fetch_all_OligoFeatures; speeds things up greatly if only a subset of arrays is being used

Added empty get_all_Attributes method to prevent transcript attributes being returned with PredictionTranscripts. Contributed by Paul Mooney.

Added proper storing of array names - relies upon external_db.dbname being the same as oligo_array.name which currently requires some nasty manual hacking

Only use one RangeRegistry object, instead of one per transcript. Should improve speed and reduce memory footprint

changed the way the header is split for the new uniprot_sprot_varsplic.fasta
format