added xref records relevant to vectorbase array mappings (anopheles / aedes)

new methods for creating the display xref and gene descriptions by reading the core database and not just using the mapping files. This means it will be possible to add sources one at a time without trashing the display_xrefs and gene descriptions. This was previously a problem as if you are just adding a new source then only that source could be used for getting the descriptions etc.

Added ability to project gene descriptions as well as names etc. Projected descriptions are currently stored the 'old' way, i.e. in the actual gene description field rather than in the info_* fields in the xref table.

Slight change in procedure: a 'master' database must now be specified. The external_dbs.txt file is loaded into this, and this in turn is compared (id and name) with the contents of the external_db table in each of the databases to be updated.

If the database to be updated has any extra rows, a warning is given and the database is skipped.

This should help avoid unilateral changes to external_db which haven't been commited to the external_dbs.txt file in CVS being silently overwritten and causing problems down the line.

fetch_all_by_biotype  added

Change in UNIQUE index on xref results in many more GO terms (apparently) being projected, but this is because the same GO term projected from multiple sources now gets multiple rows in the xref table, whereas before, because info_type/info_text wasn't being considered, only one row would have been created.