Add basic drop-and-drop connection editing

map.h

@@ -8,6 +8,7 @@
 #include <QPixmap>
 #include <QObject>
 #include <QDebug>
+#include <QGraphicsPixmapItem>
 
 
 template <typename T>
@@ -179,6 +180,7 @@ public:
     QMap<QString, QList<Event*>> events;
 
     QList<Connection*> connections;
+    QMap<QString, QGraphicsPixmapItem*> connection_items;
     QPixmap renderConnection(Connection);
 
     QImage border_image;