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/block/clip/clip.cpp

@@ -100,16 +100,15 @@ TimeRange ClipBlock::OutputTimeAdjustment(NodeInput *input, const TimeRange &inp
   return Block::InputTimeAdjustment(input, input_time);
 }
 
-NodeValueTable ClipBlock::Value(const NodeValueDatabase &value) const
+NodeValueTable ClipBlock::Value(NodeValueDatabase &value) const
 {
   // We discard most values here except for the buffer we received
-  NodeValueTable table;
   NodeValue data = value[texture_input()].GetWithMeta(NodeParam::kBuffer);
 
+  NodeValueTable table;
   if (data.type() != NodeParam::kNone) {
     table.Push(data);
   }
-
   return table;
 }
 

app/node/block/clip/clip.h

@@ -50,7 +50,7 @@ public:
 
   virtual TimeRange OutputTimeAdjustment(NodeInput* input, const TimeRange& input_time) const override;
 
-  virtual NodeValueTable Value(const NodeValueDatabase& value) const override;
+  virtual NodeValueTable Value(NodeValueDatabase& value) const override;
 
   virtual void Retranslate() override;