add support for solving with sparse right hand side
Merged local branch with main trunk
Add additional methods in SparseLU and Improve the naming conventions

--HG--
rename : Eigen/src/SparseLU/SparseLUBase.h => Eigen/src/SparseLU/SparseLUImpl.h
rename : Eigen/src/SparseLU/SparseLU_Matrix.h => Eigen/src/SparseLU/SparseLU_SupernodalMatrix.h