[eigen] Sparse * Diagonal matrix product

[Trevor Irons <trevorirons@xxxxxxxxx>]

Greetings:

I have some code that used to compile that was like:

    VectorXd X = VectorXd::Random(5);
    DynamicSparseMatrix<double, RowMajor> D(5, 5);
    for (int i=0; i<5; ++i) D.coeffRef(i,i) = 1;
    cout << D*X.asDiagonal() << endl; // product fails to compile

The sparse times diagonal product seems to no longer be defined. 
Was removal of this functionality intentional? 

-- Trevor