Patch for ‘Coherence for lenses and open games’

• Coherence for lenses and open games, arXiv v2

I have been working on referee reports from version 1 (which was rejected for good reasons). I have uploaded an intermediate state of corrections, for the benefit of the reviewers of my extended abstract for STRING’17. This put me in the awkward position of uploading a paper that I know probably still contains some errors, although it’s less wrong than the previous version.