get GPUImageRenderer for getting options

Author: chihung93

library/src/main/java/jp/co/cyberagent/android/gpuimage/GPUImage.java

@@ -779,4 +779,8 @@ private Bitmap rotateImage(final Bitmap bitmap) {
     public interface ResponseListener<T> {
         void response(T item);
     }
+
+    public GPUImageRenderer getRenderer() {
+        return renderer;
+    }
 }