organism ordering issue in merge_organisms

[kzuberi]

The process to merge multiple single organisms databases into one multi-org db described here gets confused if the organisms to combine are not in order by id.

The workaround for now is to make sure to specify the organisms by ascending organism id with the 'orgs' config argument on the command-line.

Two fixes are necessary to the merge_organisms.py script:

• check if organism ids don't collide, if not, then never attempt to renumber them
• if they do collide, must also renumber the id of the go annotation set used for enrichment, which by convention has the same id