small docfix in pod

add non-species specific go data file. If chicken goa found else where then replace this but i could not find it.

check the species is correct. This will make the parsing a little slower for those species specific files but the same modules can now be used if you have to parse a file with a mixture of species.

Small modifications to source names so that they exactly match what's in the existing external_db table. Presence of / in Uniprot names will need to be dealt with to avoid breaking download directory creation.

Script to convert new xref mappings (which may be to translations or transcripts) to all translations

Checks for non-translation mappings in new xref file and warns that conversion script may need to be run.