assumes sq aspect ratio

[ofZach]

trying to blur a large horizontal image i saw the blur not really square.

I think the code should be something like this to fix:

blur_shader.setUniform2f("direction", 1. / pingpong[index].front->getWidth(), 0);	
....			
blur_shader.setUniform2f("direction", 0, 1. / pingpong[index].front->getHeight());