Added pan method for monot2stereo.

mono2stereo.cpp

@@ -29,6 +29,12 @@
 // Written by Holger Wirtz
 // 20191122 - inital version
 
+void Mono2Stereo::pan(float pan)
+{
+  constrain(pan, 0.0, 1.0);
+  _pan = pan;
+}
+
 void Mono2Stereo::update(void)
 {
   audio_block_t *in;

mono2stereo.h

@@ -41,7 +41,8 @@ class Mono2Stereo : public AudioStream
     }
 
     virtual void update(void);
-
+    virtual void pan(float pan);
+    
   private:
     audio_block_t *inputQueueArray[4];
     audio_block_t *out[2];