Set lastViewed on initial load

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

@@ -229,17 +229,20 @@ public class ThreadPresenter implements ChanLoader.ChanLoaderCallback, PostAdapt
 
         if (loadable.isThreadMode()) {
             int postsSize = result.posts.size();
+
+            if (loadable.lastViewed < 0) {
+                loadable.lastViewed = result.posts.get(result.posts.size() - 1).no;
+            }
+
             if (notificationPostCount < 0) {
                 notificationPostCount = postsSize;
-            } else {
+            } else if (postsSize > notificationPostCount) {
-                if (postsSize > notificationPostCount) {
                 int more = postsSize - notificationPostCount;
                 notificationPostCount = postsSize;
 
                 threadPresenterCallback.showNewPostsNotification(true, more);
             }
         }
-        }
 
         chanLoader.setAutoLoadMore(isWatching());
         showPosts();