Exonerate output files now indude sequence type (dna or prot) to allow determination of what sort of Ensembl objects to link them to when building the object_xref table.

Documentation.

calculate_num_jobs now returns at least 1 job.

 - xref.txt - contains xrefs that were mapped to e! objects during the mapping run
 - external_db.txt - contains the unique list of xref sources from the xrefs above in a format suitable for loading into the existing external_db table

Doesn't do dependent xrefs yet.

Disabled automatic loading of object_xrefs etc, now written to file.