\tempo -bug and feature request

[Heikki Johannes Junes]

I could vary tempo in a single piece by just putting \tempo 4 = 80 insides
notes. However, the parsed understood that some extra space was included
and notes in paper were off by an extra s4.

Example:

\score {
  \notes {
    \tempo 4 = 60
    c4 c c c
    \tempo 4 = 80
    c c c c
    \tempo 4 = 100
    c c c c
    \tempo 4 = 120
    c c c c
  }
  \paper {}
  \midi {}
}

Caused:

/home/hjunes/notes/test/testN.ly:3:14: warning: Junking event:
`TempoEvent':
    \tempo 4 =
               60

/home/hjunes/notes/test/testN.ly:5:14: warning: Junking event:
`TempoEvent':
    \tempo 4 =
               80

/home/hjunes/notes/test/testN.ly:7:14: warning: Junking event:
`TempoEvent':
    \tempo 4 =
               100

/home/hjunes/notes/test/testN.ly:9:14: warning: Junking event:
`TempoEvent':
    \tempo 4 =
               120


I think the syntax proposed in the example is very concise and it could be
allowed. It is quite an important feature, how to vary tempo. Finally,
there was a way, I tested it, and found couple of errors.

My proposal is that

  \tempo 4 = 120

could be used just to change tempo. And, MM (Maelzel's Metronome,

  \MM 4 = 120

to change tempo and print also 'a quarter note equals 120' above staff.

To conclude there was bug concerning \tempo and feature request for \MM.

      Heikki Junes