KERML_ — isComposite, semantics

Composite features (Feature::isComposite=true) are described as

Values of a composite feature, on each instance of the feature's domain, cannot exist after the featuring instance ceases to exist. This only applies to values at the time the instance goes out of existence, not to other things in the co-domain that might have been values before that.

but this semantics is not math/modeled and Core does not include models of time.

Add isComposite semantics

This resolution adds

• informal semantics (in text) for single "ownership" via composite features (values of composite features cannot be values of other composite features that are not featured by the same composing instance).
• modeled semantics for the above and for the existing informal "destruction" semantics (values of composite features at the time their composing occurrences end also end at that time).