Use subscriptions in onCreate method in CataloguePresenter

app/src/main/java/eu/kanade/mangafeed/util/PageBundle.java

@@ -0,0 +1,12 @@
+package eu.kanade.mangafeed.util;
+
+public class PageBundle<T> {
+
+    public final int page;
+    public final T data;
+
+    public PageBundle(int page, T data) {
+        this.page = page;
+        this.data = data;
+    }
+}

app/src/main/java/eu/kanade/mangafeed/util/RxPager.java

@@ -0,0 +1,32 @@
+package eu.kanade.mangafeed.util;
+
+import rx.Observable;
+import rx.subjects.PublishSubject;
+
+public class RxPager {
+
+    private final int initialPageCount;
+    private final PublishSubject<Integer> requests = PublishSubject.create();
+    private int requestedCount;
+
+    public RxPager() {
+        this(1);
+    }
+
+    public RxPager(int initialPageCount) {
+        this.initialPageCount = initialPageCount;
+    }
+
+    public void requestNext(int page) {
+        requests.onNext(page);
+    }
+
+    public Observable<Integer> pages() {
+        return requests
+            .concatMap(targetPage -> targetPage <= requestedCount ?
+                    Observable.<Integer>never() :
+                    Observable.range(requestedCount, targetPage - requestedCount))
+            .startWith(Observable.range(0, initialPageCount))
+            .doOnNext(it -> requestedCount = it + 1);
+    }
+}