-add set...() methods and their documentation; remove Generic

-use row-major traversal when the number of columns is fixed
 and the number of rows is dynamic
-other minor changes

Eigen/src/Core/Map.h

@@ -86,7 +86,7 @@ template<typename MatrixType> class Map
     
   protected:
     const Scalar* m_data;
-    int m_rows, m_cols;
+    const int m_rows, m_cols;
 };
 
 /** This is the const version of map(Scalar*,int,int). */