Fix some of the effects in qmlvideofx

* TiltShift was sometimes applying the effect in the wrong place.
* Blur had some QML properties duplicated
* Blur kernel wasn't quite summing to 1, and was applying opacity twice
* The target width for the second pass was incorrect, so it was blending
darkness, resulting in a dreary image.

Change-Id: Ib8ba93d979c597cf4d225b3d24d26a22d0cdffc2
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

examples/video/qmlvideofx/shaders/tiltshift.fsh

@@ -67,7 +67,7 @@ void main()
 {
     vec2 uv = qt_TexCoord0.xy;
     vec3 col;
-    if (uv.x < dividerValue && uv.y >= 0.4 && uv.y <= 0.6)
+    if (uv.x > dividerValue || (uv.y >= 0.4 && uv.y <= 0.6))
         col = texture2D(source, uv).rgb;
     else
         col = blur();