@Alex – sorry for the delay but I have to finish few features to make the prerelease version usable.
You can download prerelease of v.0.37 here: https://cdn.getpublii.com/prerelease/Publii-0.37.0.dmg – this version restores the “Use relative URLs” switcher under server setttings.
If you will find any problems with relative URLs – feel free to report me them.