Add functionality to ensure that the basic system works

There are some things missing:

- Configuration
- Resuming downloads when the list doesn't scroll past the window

src/CMakeLists.txt

@@ -4,9 +4,9 @@ set(danbooru_client_SRCS
     danbooruconnectwidget.cpp
     model/danboorupostdelegate.cpp
     model/danboorupostmodel.cpp
-    test.cpp
-#     mainwindow.cpp
-#     danbooru_client.cpp
+#     test.cpp
+    mainwindow.cpp
+    danbooru_client.cpp
      testwidget.cpp
      testpostdata.cpp
  )