I re-factored GaussNewton so the linear least squares solver is pluggable, and improved the efficiency of the existing implementations. If we create an interface for solving a linear least squares problem then users could provide their own implementations.
I created a patch for each commit in my tree. Let me know if you would like them in a different format.
The patches have been applied (r1569905, r1569906 and r1569907) without any problems.
Thanks for the patches!
Closing all resolved issue now available in released 3.3 version.