imageviewer: check starting position bounds.

use equalUrl for finding the correct image.

Clover/app/src/main/java/org/floens/chan/core/presenter/ImageViewerPresenter.java

@@ -67,7 +67,7 @@ public class ImageViewerPresenter implements MultiImageView.Callback, ViewPager.
 
     public void showImages(List<PostImage> images, int position, Loadable loadable) {
         this.images = images;
-        selectedPosition = position;
+        selectedPosition = Math.max(0, Math.min(images.size() - 1, position));
         this.loadable = loadable;
 
         progress = new ArrayList<>(images.size());

Clover/app/src/main/java/org/floens/chan/core/presenter/ThreadPresenter.java

@@ -430,7 +430,7 @@ public class ThreadPresenter implements ChanLoader.ChanLoaderCallback, PostAdapt
                 for (int j = 0; j < item.images.size(); j++) {
                     PostImage image = item.images.get(j);
                     images.add(image);
-                    if (image == postImage) {
+                    if (image.equalUrl(postImage)) {
                         index = images.size() - 1;
                     }
                 }