-merge patch from Gael Guennebaud adding NumTraits for long long

and long double.
-define scalar-multiple operators only for the current Scalar type;
 thanks to Gael for expaining how to make the compiler understand
 when automatic casting is needed.
-take ScalarMultiple take only 1 template param, again.
 We lose some flexibility especially when dealing with complex numbers,
 but we gain a lot of extensibility to new scalar types.

Eigen/src/Core/Dot.h

@@ -121,7 +121,7 @@ typename NumTraits<Scalar>::Real MatrixBase<Scalar, Derived>::norm() const
   * \sa norm()
   */
 template<typename Scalar, typename Derived>
-const ScalarMultiple<typename NumTraits<Scalar>::Real, Derived>
+const ScalarMultiple<Derived>
 MatrixBase<Scalar, Derived>::normalized() const
 {
   return (*this) / norm();