New approach to interning. Before, InternerMultimap.intern() was passed
a linkFactory and was therefore responsible for creating the
uptype-object. The result was passed to the client who was responsible
to register the result. 
In the new approach, each type has its own Interner which is responsible
to manage the links to its down-types and its up-types. See how
StringInterner manages the uplinks and how StringCategory manages its
downlinks...
advanced implementation of the StringCategory interner and started to
port FormStore...realized that ArrayEntity and OnArrayList also need
interners
deleted EntityLoaded (this can probably be replaced with AtomicEntity)
and references to it. Created AtomicEntity and used it in StringCategory
overridden equals and hashCode in ArrayEntity, using java.lang.Objects.
NOTE: equals must be reset according based on Form/Entity, whether the
Category of a Domain matters, etc.