Mac installers now available

[ColinH1972]

Calion, just use goto: press G, then click the tile.

[cazfi]

Beyond that, I ran into the issue that any of the packages can change at any time, and there's no way to get any but the latest version. And a change can break the build - I set up a shell script to download the packages and build from a freeciv source tarfile, and it worked until one day it didn't because a changed package broke the build.

For the same reproducibility problem with msys2, we maintain our own msys2 environment snapshot to use when making official/reproducible builds. See doc/README.msys2