create new collection using an array of entities.
added toDelete for massive delete. changed del->remove.
implemented setRelation for JoinBy relation.
join entity structure.
created/modified fr2gr model/entity/csv.
initial test for JoinBy relation.
packed should work, fixed phpdoc.
fixed construction of $info. case for no relation.
made collection iteratable with foreach using IteratorAggregate.
keep join entities inside JoinBy relation object as $joiner.
check if joiner is set; set newCollection if not set.
simple test on link().
more test on late-linking.