Opt out of up vector guess when intake not yet ready.

TweakScale rescales things during OnLoad when reverting to launch. At this point moduleResourceIntakes are not yet fully set up, and FARGeoUtil.GuessUpVector throws a NullReferenceException.

It may be that this is a more general problem and should be fixed in TweakScale instead (by not calling updaters and using exponents until the first call to Update, e.g.). Comments?