Add standard error check for multilevel example: aka mutligroup state space.
Add standard error check for multilevel example: aka mutligroup state space.

jpritikin/OpenMx,jpritikin/OpenMx,JuKa87/OpenMx,mhunter1/OpenMx,jpritikin/OpenMx,mhunter1/OpenMx,mhunter1/OpenMx,JuKa87/OpenMx,JuKa87/OpenMx,JuKa87/OpenMx,mhunter1/OpenMx,jpritikin/OpenMx,mhunter1/OpenMx,mhunter1/OpenMx,jpritikin/OpenMx,JuKa87/OpenMx,jpritikin/OpenMx,JuKa87/OpenMx