Altering the sounding duration of notes.( was Re: XML anatomy)

[Richard Shann]

To supplement the Jazz swing and grace note playback implementation
that are now in the Staffs->Playback menu I've now provided a more low
level command that lets you alter the sounding duration of a single
note/chord or rest. It's in the Notes->Playback menu.
Note that it is up to you to alter the duration of the following
note(s) to ensure that the music stays in sync with other parts.

Richard