nodes can now be connected through the node editor

nodes/nodeedge.h

@@ -0,0 +1,39 @@
+#ifndef NODEEDGE_H
+#define NODEEDGE_H
+
+#include <memory>
+
+class EffectRow;
+
+class NodeEdge;
+using NodeEdgePtr = std::shared_ptr<NodeEdge>;
+
+class NodeEdge
+{
+public:
+  /**
+   * @brief NodeEdge Constructor
+   *
+   * Creates a node edge and stores its two connections.
+   *
+   * This should not be used directly. Use the static function EffectRow::ConnectEdge instead.
+   *
+   * @param output
+   *
+   * Output/from EffectRow that this edge "starts" at
+   *
+   * @param input
+   *
+   * Input/to EffectRow that this edge "ends" at
+   */
+  NodeEdge(EffectRow* output, EffectRow* input);
+
+  EffectRow* output();
+  EffectRow* input();
+
+private:
+  EffectRow* output_;
+  EffectRow* input_;
+};
+
+#endif // NODEEDGE_H