moved several files around

Mostly moved classes that became node derivatives into the node/ folder.

app/node/generator/solid/solid.h

@@ -31,6 +31,8 @@ class SolidGenerator : public Node
 public:
   SolidGenerator();
 
+  NODE_DEFAULT_DESTRUCTOR(SolidGenerator)
+
   virtual Node* copy() const override;
 
   virtual QString Name() const override;