Optionally return cursor for table `results` value

This release introduces a couple of new options for \Tripod\Mongo\Composites\Tables->getTableRows():

• returnCursor => true: will return a \MongoDB\Driver\Cursor as the value of the results property.
• includeCount => false: will skip getting a total hit count - avoids a performance hit if returning all results via a cursor - the actual individual results returned are identical to returning them as an array
• documentType => '{some BSONUnserializable class}': gives the ability to rewrite the table row documents as returned from the cursor, so no post-processing is necessary.