Collections: Do not describe same linked resources multiple times

[tpluscode]

When a collection is queried, the query:memberInclude patterns are already processed in the query for collection members. Later, query:include of all individual members are fetched. There may be cases when same resources would be loaded twice if the query:memberInclude and query:include overlapped

<> a ex:Collection ; hydra:member <A> .

<A> a ex:Person ; foaf:knows <B> .

ex:Collection
  query:memberInclude [ query:path foaf:knows ] . 

ex:Person
  query:include [ query:path foaf:knows ] .

The resource <B> would be described twice. First, following the same path defined in both includes.