Standardize name of bioentity column

[cmungall]

Internally in golr the subject of an annotation is the bioentity. The value can be gene, protein, other gene product, complex. We need a standardized label for this -see #194.

Gene/product is what we currently have in the annotation view. This is probably better than weird GO terminology like Acc or GO_DB_Obj.

However, technically it's not quite correct when we have complexes. But perhaps we can live with this infelicity?

[kltm]

#147 is also possibly relevant here.