various node UI improvements

app/node/input.h

@@ -27,7 +27,7 @@
 class NodeInput : public NodeParam
 {
 public:
-  NodeInput(Node *parent);
+  NodeInput();
 
   virtual Type type() override;
 
@@ -43,6 +43,8 @@ public:
   bool keyframing();
   void set_keyframing(bool k);
 
+  const QList<DataType>& inputs();
+
 private:
   QList<DataType> inputs_;