Fixed compilation error in Matrix4.

Didn't notice it until now because the function wasn't used before at
all.

src/Math/Matrix4.h

@@ -111,7 +111,7 @@ template<class T> class Matrix4: public Matrix<T, 4> {
         }
 
         /** @copydoc Matrix::Matrix(ZeroType) */
-        inline constexpr explicit Matrix4(typename Matrix<T, 4>::ZeroType): Matrix<T, 3>(Matrix<T, 3>::Zero) {}
+        inline constexpr explicit Matrix4(typename Matrix<T, 4>::ZeroType): Matrix<T, 4>(Matrix<T, 4>::Zero) {}
 
         /** @copydoc Matrix::Matrix(IdentityType, T) */
         inline constexpr explicit Matrix4(typename Matrix<T, 4>::IdentityType = Matrix<T, 4>::Identity, T value = T(1)): Matrix<T, 4>(