* Clean up seventh group of historical resource properties
* Change KSPCalendar download link to archive.org
This PR changes every `x_ci` to `ci`, `x_preview` to `x_screenshot`, and `x_curse` to `curse` (and adjusts the `spec_version` where needed).
Thanks to @V1TA5, we have a mirror of the freely redistributable mods
from KS. This change re-writes extant CKAN metadata files that have
free licenses to use the i.52k.de server.
Created by running 1f3e252e9ae3dbad6e123d72dd1a255e32484a6e of
kspstuff-migrate.pl in https://github.com/pjf/KS-KSPStuff-Migration