small update

Former-commit-id: d87116015c18f7936824fe66dc06a3d56139bf6a

include/igl/viewer/ViewerCore.cpp

@@ -7,11 +7,12 @@
 // obtain one at http://mozilla.org/MPL/2.0/.
 
 #include "ViewerCore.h"
-#include <igl/quat_to_mat.h>
-#include <igl/massmatrix.h>
-#include <Eigen/Geometry>
+
 #include <iostream>
+#include <Eigen/Geometry>
 
+#include <igl/quat_to_mat.h>
+#include <igl/massmatrix.h>
 
 IGL_INLINE Eigen::Matrix4f lookAt (
                         const Eigen::Vector3f& eye,