Adjust voting rule changes again

* If `kartvoterulechanges` is set to `Always`, the third option is always the opposite gametype, even if Encore is unlocked - that will now be present on the second option instead.
    * This is both for consistancy with having Encore inaccessible on your gamedata, and a response to community feedback.
* The `kartencore` cvar being turned on will now be reflected in gametype rule changes from Battle to Race. This plugs one last hole in its area of effect for Race tracks.