Gene locations

[eparejatobes]

We have an enum for UniProt gene locations, but no property storing this data.

• Where this should go
• Add the corresponding property

[eparejatobes]

The gene location corresponds to the gene, which do not actually exist in UniProt. The possible places where this property could go are

1. entry protein vertices
2. gene product edges

Gene (names) are not an option because of possible conflicts between equally named genes with different locations. I'm following 2. above as a lesser evil.

[eparejatobes]

LGTM