Register file fetch using database name

[Tom Goddard]

The current database fetch registration code only uses the file format name, not the database name. The fetch code should use separate database name and format name, for instance the EM Databank database name might be EMDB while the map file format it provides is CCP4. Several databases might return the same file format, for instance, Modbase, NDB, SCOP, PDB all return PDB format files so it is not sufficient to associate the fetch function with the file format name as is done in the current code.

[Greg Couch]

Tom did this. Changed to not be contained within a session so toolshed metadata can be used to register fetch routines.