adapt code to LRC API change

LRC API (Singleton's implementation) has changed.
This patch adapats the code to these changes.
Moslty changes deferencement '->' for direct access '.'

Tuleap: #44
Change-Id: Ic87b1306a1239fdb8a6af0affe1ecbc1d16f609c
diff --git a/src/historyview.cpp b/src/historyview.cpp
index 43a8633..2992494 100644
--- a/src/historyview.cpp
+++ b/src/historyview.cpp
@@ -160,7 +160,7 @@
  *
  *     if (idx.isValid()) {
  *         g_debug("deleting history item");
- *         CategorizedHistoryModel::instance()->removeRow(idx.row(), idx.parent());
+ *         CategorizedHistoryModel::instance().removeRow(idx.row(), idx.parent());
  *     }
  * }
  */
@@ -387,7 +387,7 @@
     gtk_tree_view_set_enable_search(GTK_TREE_VIEW(treeview_history), FALSE);
 
     /* instantiate history proxy model */
-    priv->q_sorted_proxy = CategorizedHistoryModel::SortedProxy::instance();
+    priv->q_sorted_proxy = &CategorizedHistoryModel::SortedProxy::instance();
 
     /* for now there is no way in the UI to pick whether sorting is ascending
      * or descending, so we do it in the code when the category changes */