build: reanimate the dead

Fix build with ndn-cxx 0.7.1 and ChronoSync 0.5.3

* Adapt to new API
* Upgrade to Qt5
* Several other bugs

Refs: #4563, #4087
Change-Id: Ic55d687caade08f557f9b9ec3e9569bc96798710
diff --git a/src/digest-tree-scene.hpp b/src/digest-tree-scene.hpp
index 0e69528..562feeb 100644
--- a/src/digest-tree-scene.hpp
+++ b/src/digest-tree-scene.hpp
@@ -12,7 +12,7 @@
 #ifndef CHRONOCHAT_DIGEST_TREE_SCENE_HPP
 #define CHRONOCHAT_DIGEST_TREE_SCENE_HPP
 
-#include <QtGui/QGraphicsScene>
+#include <QGraphicsScene>
 #include <QColor>
 #include <QMap>
 
@@ -44,7 +44,7 @@
   Q_OBJECT
 
 public:
-  DigestTreeScene(QWidget *parent = 0);
+  DigestTreeScene(QObject *parent = 0);
 
   void
   processSyncUpdate(const std::vector<chronochat::NodeInfo>& nodeInfos,