Tempo changes for MIDI output.

[Matthias Kilian]

Hi,

I want tempo changes to affect MIDI output only, i.e. there should be no
metronome marks in the output. Just removing the Metronome_mark_engraver
works:

  \paper {
    \translator {
      \ScoreContext
      \remove Metronome_mark_engraver
    }
  } 

However, now I get annoying warnings:

    /home/kili/lily/chaconne.ly:251:16: warning: Junking event:
    `MetronomeChangeEvent':
      | \tempo 4 = 7
                      5 <d f>16_.])

is there any clean way to turn this warnings off, or perhaps a completely
other way to change the tempo only for the MIDI output?

Ciao,
        Kili