removed all dependence on NodeOutputs

If Nodes only have the one output, we don't need to do so much differentiation
between them. Previous iteration used outputs as like a distinct function
within a Node (e.g. length output would return one result, buffer output would
produce a different result - each run different code to produce their results).
Now in this iteration, it's more accurate to say a Node is just one function
(which seems more appropriate for a node system anyway).

app/node/input/media/audio/audio.cpp

@@ -2,8 +2,6 @@
 
 AudioInput::AudioInput()
 {
-  samples_output_ = new NodeOutput("samples_out");
-  AddParameter(samples_output_);
 }
 
 Node *AudioInput::copy() const
@@ -31,11 +29,6 @@ QString AudioInput::Description() const
   return tr("Import an audio footage stream.");
 }
 
-NodeOutput *AudioInput::samples_output()
-{
-  return samples_output_;
-}
-
 NodeValueTable AudioInput::Value(const NodeValueDatabase &value) const
 {
   return value[footage_input_];