Add pets as sharable

[dddeeefff]

I think it would be a nice feature to have pets able teleport with you on certain worlds rather than being locked into the world you tamed them in.

I haven't done a tonne of research on this before suggesting this, but I don't think it's a feature in the core for pets to teleport to any world - I couldn't see a permissions node for it on the wikis

[dumptruckman]

This would be a neat feature. I'm not entirely sure it's appropriate for MV-Inv to cause pets to follow you on teleport but if something else did do this, it would only make sense for MV-Inv to limit pets being able to follow you to worlds that share pets.