OpenTTD sources are still written in a way to work down to OSX 10.4 or so, as long as you can obtain a C++11 capable compiler. 10.9 is the minimal useful C++11 target using only Apple stuff out-of-the-box.
This release pipeline creates all the official release binaries,
and publishes them as artifacts. Currently it can only produce
nightlies and custom builds; stable/testing release binaries are
untested.
This commit also splits up the pipeline in small bits, to both
improve readability, and to share code with the CI pipeline where
possible.
