node: fixed issue with "taking" values from input tables

As opposed to simply leaving all values in the table, nodes can now "take"
values that they use to free up memory (e.g. "taking" input buffers if they're
used to produce an output buffer).

This is a fairly large change, expect regressions.

app/node/node.h

@@ -332,7 +332,7 @@ public:
    * corresponding output if it's connected to one. If your node doesn't directly deal with time, the default behavior
    * of the NodeParam objects will handle everything related to it automatically.
    */
-  virtual NodeValueTable Value(const NodeValueDatabase& value) const;
+  virtual NodeValueTable Value(NodeValueDatabase& value) const;
 
   /**
    * @brief Return whether a parameter with ID `id` has already been added to this Node
@@ -341,7 +341,7 @@ public:
 
   NodeOutput* output() const;
 
-  virtual NodeValue InputValueFromTable(NodeInput* input, const NodeValueDatabase& db) const;
+  virtual NodeValue InputValueFromTable(NodeInput* input, NodeValueDatabase &db, bool take) const;
 
   const QPointF& GetPosition();