don't use track as the time chooser

This design, while not completely illogical, seems to betray the DAG design
and borders on impossible to actually recompile. The plan is to build this
functionality into the renderer instead.

app/node/output/track/track.cpp

@@ -196,16 +196,6 @@ QVariant TrackOutput::Value(NodeOutput *output, const rational &in, const ration
   if (output == track_output_) {
     // Set track output correctly
     return PtrToValue(this);
-  } else if (output == buffer_output()) {
-    ValidateCurrentBlock(in);
-
-    if (current_block_ != this) {
-      // At this point, we must have found the correct block so we use its texture output to produce the image
-      return current_block_->buffer_output()->get_value(in, out);
-    }
-
-    // No texture is valid
-    return 0;
   }
 
   // Run default node processing

app/node/output/track/track.h

@@ -174,8 +174,6 @@ private:
 
   NodeOutput* track_output_;
 
-  NodeOutput* block_list_output_;
-
   TrackType track_type_;
 
   int block_invalidate_cache_stack_;