[Open-bio-l] proposed change to biosql schema: seqfeature_dbxref

[Chris Mungall]

I have some uncommitted changes to biosql - I have added a
seqfeature_dbxref table for linking features to their xrefs.

Currently these just go in to seqfeature_qualifier_value as strings eg
"FBgn:0000001"

I think it's much more useful to store these as dbxrefs, in order to, say
get all genes with an OMIM identifier (this would have to be done with
string matching now)

I have corresponding changes in bioperl-db for updating this table (the
dbxref also goes in as a qualifier_value, so there is some redundancy)

how do we want to handle syncing code/schema? if i commit the bioperl-db
code and someone uses it on an older schema it will break.