message: Expand a doxygen comment in class MatrixFunctionCoefficient.
diff: @@ -419,7 +419,7 @@ public:
  mat.SetSize(0);
  }
  - /// Construct a constant matrix coefficient
  + /// Construct a constant matrix coefficient times a scalar Coefficient
  MatrixFunctionCoefficient(const DenseMatrix &m, Coefficient &q)
  : MatrixCoefficient(m.Size()), Q(&q)
  {
  