[DCP-o-matic] Request for macOS testing

Hi all, I have a new version of DCP-o-matic here: https://dcpomatic.com/rc-download There have been some bug fixes, but more importantly this version is built against a newer version of the macOS SDK than previous versions, and has a number of changes to comply with changes in Apple's notorization requirements. I was hoping to leave these fixes until 2.16.0 but Apple have quietly changed some things and forced my hand. I would be very grateful if anybody could take the time to test it. It won't run on anything earlier than macOS Mavericks but I will upload a different version for old OS versions soon. Thank you! Carl