code: use macros for default node functions

Easier to maintain

app/node/input/time/timeinput.cpp

@@ -28,11 +28,6 @@ TimeInput::TimeInput()
 {
 }
 
-Node *TimeInput::copy() const
-{
-  return new TimeInput();
-}
-
 QString TimeInput::Name() const
 {
   return tr("Time");

app/node/input/time/timeinput.h

@@ -27,13 +27,11 @@ namespace olive {
 
 class TimeInput : public Node
 {
-    Q_OBJECT
+  Q_OBJECT
 public:
   TimeInput();
 
-  NODE_DEFAULT_DESTRUCTOR(TimeInput)
-
-  virtual Node* copy() const override;
+  NODE_DEFAULT_FUNCTIONS(TimeInput)
 
   virtual QString Name() const override;
   virtual QString id() const override;

app/node/input/value/valuenode.h

@@ -31,12 +31,7 @@ class ValueNode : public Node
 public:
   ValueNode();
 
-  NODE_DEFAULT_DESTRUCTOR(ValueNode)
-
-  virtual Node* copy() const override
-  {
-    return new ValueNode();
-  }
+  NODE_DEFAULT_FUNCTIONS(ValueNode)
 
   virtual QString Name() const override
   {