code: use macros for default node functions

Easier to maintain

app/node/block/clip/clip.cpp

@@ -61,11 +61,6 @@ ClipBlock::ClipBlock() :
   SetEffectInput(kBufferIn);
 }
 
-Node *ClipBlock::copy() const
-{
-  return new ClipBlock();
-}
-
 QString ClipBlock::Name() const
 {
   if (track()) {

app/node/block/clip/clip.h

@@ -37,9 +37,7 @@ class ClipBlock : public Block
 public:
   ClipBlock();
 
-  NODE_DEFAULT_DESTRUCTOR(ClipBlock)
-
-  virtual Node* copy() const override;
+  NODE_DEFAULT_FUNCTIONS(ClipBlock)
 
   virtual QString Name() const override;
   virtual QString id() const override;