[models] Make userInfo writeable.
[core] Modernization, /// deletion, docs clarification.
[core] Modernize NIActions+Subclassing.h.
Merge branch 'models'
[core] Tidy up docs in NICommonMetrics.
[core] Delete all /// dividers in NICommonMetrics.
[core] Deprecate NILinkedList in favor of NSMutableOrderedSet.