Make Control_Surface a MIDI Sink/Source

When disconnecting a MIDI Source, also disconnect the Pipe from the Sink
(and vice versa)

examples/3. MIDI Interfaces/Dual-MIDI-Interface/Dual-MIDI-Interface.ino

@@ -2,6 +2,17 @@
  * This example demonstrates how to group together two or more MIDI interfaces,
  * so you can send the MIDI output over both MIDI USB and 5-pin DIN MIDI, for 
  * example. MIDI input is received from all interfaces as well.
+ * 
+ * Also have a look at the @ref MIDI_Pipes-Routing.ino example and the 
+ * @ref MIDI_Pipe documentation for more information about MIDI routing.  
+ * Control Surface can be used as both a MIDI sink and a MIDI source.
+ * 
+ * When you call `Control_Surface.begin()`, it automatically connects itself to 
+ * the default MIDI interface (@ref MIDI_Interface::getDefault()).  
+ * If you want to route everything manually, you have to connect it before 
+ * calling `Control_Surface.begin()`, or you have to disconnect the default 
+ * pipes before connecting your own, using 
+ * @ref Control_Surface_::disconnectMIDI_Interfaces().
  *
  * @boards  AVR USB, Due, Teensy 3.x
  * 
@@ -35,20 +46,18 @@
 USBMIDI_Interface usbmidi;
 HardwareSerialMIDI_Interface serialmidi = {Serial1, MIDI_BAUD};
 
-// And group them together
-MultiMIDI_Interface<2> midi = {{&usbmidi, &serialmidi}};
-
-// The MIDI interface that was instantiated last will be used as the
-// default MIDI interface by Control_Surface.
-// To override the default, you can use the following line in your setup:
-//    `midi.setAsDefault();`
-// where `midi` is the MIDI interface you want to set as the default.
+// Create a MIDI pipe factory to connect the MIDI interfaces to Control Surface
+BidirectionalMIDI_PipeFactory<2> pipes;
 
 // Add some MIDI elements to show that the MIDI interfaces actually work
 CCPotentiometer pot = {A0, MIDI_CC::General_Purpose_Controller_1};
 NoteValueLED led = {LED_BUILTIN, 0x3C};
 
 void setup() {
+  // Manually connect the MIDI interfaces to Control Surface
+  Control_Surface | pipes | usbmidi;
+  Control_Surface | pipes | serialmidi;
+  // Initialize Control Surface _after_ connecting the interfaces
   Control_Surface.begin();
 }
 

examples/Extending-the-library/Custom-MIDI-Output-Element/Custom-MIDI-Output-Element.ino

@@ -69,9 +69,9 @@ class MyNoteButton : public MIDIOutputElement {
   void update() final override {
     AH::Button::State state = button.update();               // Read the button
     if (state == AH::Button::Falling) {                      // if pressed
-      Control_Surface.MIDI().sendNoteOn(address, velocity);  // → note on
+      Control_Surface.sendNoteOn(address, velocity);  // → note on
     } else if (state == AH::Button::Rising) {                // if released
-      Control_Surface.MIDI().sendNoteOff(address, velocity); // → note off
+      Control_Surface.sendNoteOff(address, velocity); // → note off
     }
   }