tidy up how midi_input is set/accessed from plugins, nicer complaining when the shader gadget plugins arent present, and feedback plugin now takes most of its config (which notes to light up) by reading the midi config

data_centre/plugin_collection.py

@@ -213,9 +213,9 @@ class PluginCollection(object):
     def actions(self):
         return self.message_handler.actions
 
-    """@property
+    @property
     def midi_input(self):
-        return self.data.midi_input"""
+        return self.data.midi_input
 
     def __init__(self, plugin_package, message_handler, data):
         """Constructor that initiates the reading of all available plugins