Second Level Grouping not Working with Orthogonal Data

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create Empty Table With Two Level Grouping setup to load orthogonal data 
from objects(http://datatables.net/examples/ajax/orthogonal-data.html).
2. Have JS DataSource that is an Array of Objects.
3. Apply Issue #34.
4. Do Api Call rows.add(dataSource).draw();.

What is the expected output? What do you see instead?
Second Level Grouping doesn't work correctly.
Every row is it's own group.
Second Level Group title is undefined for all rows.

First Level Grouping and everything else appears to work as expected.

What version of the product are you using? On what operating system?
1.2.9
Windows 7 with Chrome Browser.

Please provide any additional information below.

Original issue reported on code.google.com by spinnern...@gmail.com on 13 May 2014 at 12:37

[GoogleCodeExporter]

Fix #31 needs to be applied to secondary grouping.  It fixes this problem.

Original comment by spinnern...@gmail.com on 2 Jun 2014 at 9:43