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/block/block.cpp

@@ -26,11 +26,6 @@ Block::Block() :
   previous_(nullptr),
   next_(nullptr)
 {
-  block_output_ = new NodeOutput("this_out");
-  AddParameter(block_output_);
-
-  buffer_output_ = new NodeOutput("buffer_out");
-  AddParameter(buffer_output_);
 }
 
 QString Block::Category() const
@@ -109,16 +104,6 @@ void Block::set_next(Block *next)
   next_ = next;
 }
 
-NodeOutput *Block::buffer_output() const
-{
-  return buffer_output_;
-}
-
-NodeOutput *Block::block_output() const
-{
-  return block_output_;
-}
-
 const rational &Block::media_in() const
 {
   return media_in_;