Fix spurious error playing initial grace notes (issue 1412).

Fix spurious error playing initial grace notes (issue 1412).

This happens because the MIDI output starts at tick 0, regardless of when the first event is. Initial grace notes start start at negative ticks, so midi_walker::output_event thinks they're out of order. Fixed by starting at the first event.

Note that if a piece starts with a rest, the first event will be the first note, so we'll now skip the rest. To preserve initial rests, change the last line to:

  last_tick_ = items_.empty () ? 0 : min(items_[0]->audio_column_->ticks (), 0);

[janek, 2013-11-25 13:59:10]

I think we shouldn't skip rests by default.

Other than that, it's nice to see this chnage!

Janek

[Devon Schudy, 2013-11-25 14:13:15]

janek.lilypond@gmail.com wrote:
> I think we shouldn't skip rests by default.

They're not skipped. I thought they were, because Timidity skips them,
but they're intact in the MIDI file — see comments on issue 1412.

[Keith, 2013-11-29 16:08:54]

Devon, 
I set up the latest-posted versions of your two patches that have finished
review, ready to push to the repository with headers as below, with the actual
email address being the one you used for discussion here.

Author: Devon Schudy <email>
    Grace notes: only shorten previous note if overlapping

Author: Devon Schudy <email>
    Fix spurious error playing initial grace notes (issue 1412)