Add additional methods in SparseLU and Improve the naming conventions

Eigen/src/SparseLU/SparseLU_kernel_bmod.h

@@ -12,6 +12,7 @@
 #define SPARSELU_KERNEL_BMOD_H
 
 namespace Eigen {
+namespace internal {
   
 /**
  * \brief Performs numeric block updates from a given supernode to a single column
@@ -111,6 +112,7 @@ template <> struct LU_kernel_bmod<1>
   }
 };
 
-} // end namespace Eigen
+} // end namespace internal
 
+} // end namespace Eigen
 #endif // SPARSELU_KERNEL_BMOD_H