Suggestion: add a \score { } block in musicxml2ly output

[Valentin Villenave]

Greetings Reinhold, hi everybody,

on the French list today:

a user: "how can I get a MIDI file from a musicxml file?"

me: "just run musicxml2ly, then add \midi {} to your .ly file, in the
\score {} block."

him: "there is no \score block"

me (in petto): "hmm... perhaps we should consider having a \score
block by default in musicxml2ly output."

... or even add a \layout {} and _midi {} block, for what it's worth.

I had a look at the source; I thought maybe we could add something in
musicxml2ly.py around the line 2473. But then, IANAP; and I don't know
what's the preferred method to do that.

Cheers,
Valentin