Started the implementation of Rwp cost function.  Refs #7476.
Checkpointing work.  Refs #7476.
Checkpointing work.  Refs #7476.

Implemented the Hessian matrix and Derivative vector.  It works with
non-Levenberg-Marquadt minimzers.  The result looks fine.
Modifed to be inherited.  Refs #7476.

Modify CostFuncLeastSquare such that CostFuncRwp can inherit from it.
Changed inheritance.  Refs #7476.

Made CostFuncRwp inherit from CostFuncLeastSquares other than
CostFuncFitting.
Added some unit tests related.  Refs #7476.
Added class variable for cost function factor.  Refs #7476.
Merge branch 'feature/7476_new_costfun_rwp' into develop