Issue title: NormalMapping sample Mesh view
 Issue body: In the mesh view mode the wireframe output is not rendered. 
 Comments: 
 Comment 0: UNSUBSCRIBE

On Sun, Jun 7, 2015 at 4:53 AM, gaborpapp <angelicadickerson@example.com> wrote:

> In the mesh view mode the wireframe output is not rendered.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/cinder/Cinder/issues/970>.
>

 Comment 1: [Here's the problem](https://github.com/cinder/Cinder/blob/glNext/samples/_opengl/NormalMapping/assets/wireframe_geom.glsl#L26)
Should be `gl_Position = gl_in[0].gl_Position;`

 Comment 2: This fixes it indeed. Thanks for hunting it down.
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