Add metronome to config

Former-commit-id: 38ac71aa7d4729e550372db59fa1bc4abcde4582

engine/config.py

@@ -38,6 +38,8 @@ METADATA={
     #that need to be connected internally to instrument outputs like fluidsynth
     "cboxOutputs" : 2 * 0,
 
+    #Does the program uses a metronome? In this case you need at least two cboxOutputs above
+    "metronome" : False,
 
     #Various strings for the README
     #Extra whitespace will be stripped so we don't need to worry about docstring indentation