Mention ARCHIVE=1 in Makefile.OpenArena
Merge remote-tracking branch 'upstream/master'
Fix sending pk3 download error messages to clients

Disabled in e52a492f615e1245d6d22a84d2cc100c6d2f9f88.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' into experimental/latest-libraries-sdl2