block: add access functions to primary block inputs (length/media in+out)

app/node/block/block.cpp

@@ -298,3 +298,18 @@ void Block::Retranslate()
   media_in_input_->set_name(tr("Media In"));
 }
 
+NodeInput *Block::length_input() const
+{
+  return length_input_;
+}
+
+NodeInput *Block::media_in_input() const
+{
+  return media_in_input_;
+}
+
+NodeInput *Block::media_out_input() const
+{
+  return media_out_input_;
+}
+

app/node/block/block.h

@@ -90,6 +90,10 @@ public:
 
   virtual void Retranslate() override;
 
+  NodeInput* length_input() const;
+  NodeInput* media_in_input() const;
+  NodeInput* media_out_input() const;
+
 public slots:
 
 signals: