DofAltPass cannot get Ptr

fixed by changing the header for DofAltPass

```
namespace itg
{
    /*
     * @see http://blenderartists.org/forum/showthread.php?237488-GLSL-depth-of-field-with-bokeh-v2-4-(update)
     */
    using namespace tr1;
    class DofAltPass : public RenderPass
    {
    public:
        typedef shared_ptr<DofAltPass> Ptr;
       ...
```
