Fixed a several bugs.
Several calls to the overload of Aggregate which does not take an initial value were being made without checking that the sequence was non empty.
AggregateEntities no longer include themselves in their members.
Verbs within VerbPhrase elements are now automatically endowed with their parent's subject, object , or direct object.
Merge branch 'master' of https://github.com/lasiproject/LASI.git