Fix query get cursor

[ornicar]

Make it possible to call ->getCursor() on a GROUP query.

[hex337]

This would be really helpful to fix........

[ornicar]

Jwage is right, it's written in php.net documentation http://fr.php.net/manual/fr/mongocollection.group.php

Group queries return an array, not a cursor.

[jwage]

I think the real solution here is to make our MongoCursor implementation a little more abstract and allow a lower level wrapper around an array so that we can make the returned data API consistent in Doctrine even when the mongo driver gives us inconsistent results. I will have a fix for this by the end of the week.

[jwage]

I fixed this so it will return an instance of Doctrine\ODM\MongoDB\MongoIterator but it still will just return an array for group queries because the data that is returned is not always able to be determined. It might just be a single scalar value. We don't really know. So I don't think it makes sense to wrap the result of group queries in an instance of MongoArrayIterator.