Support stdout as output

[UlyssesZh]

In alda export, outputing to stdout can be useful for piping (to timidity, ffmpeg, etc) without creating temp files. I tried --output /dev/stdout, but it does not seem to work.

[daveyarwood]

alda export actually outputs to stdout by default. Here's the example from alda export --help:

$ alda export -c "piano: c d e" > three-notes.mid
Exporting...

$ timidity -A100 --verbose three-notes.mid 
Playing three-notes.mid
MIDI file: three-notes.mid
Format: 0  Tracks: 1  Divisions: 128
14 supported events, 63910 samples, time 0:01
Init soundfonts `FluidR3_GM.sf2'
Loading SF Tonebank 0 0: Yamaha Grand Piano
Resample cache: Key 3/3(100.0%) Sample 58.0K/58.0K(100.0%)
Playing time: ~5 seconds
Notes cut: 0
Notes lost totally: 0

[UlyssesZh]

That's cool! I apparent didn't read alda export -h carefully.