`tuner': simple tuner for (presumably) stringed musical instruments.

M-x tuner pops up a window containing a representation of the
strings of your instrument.  String number keys (1-9) play the
pitch defined for the given string: you can tune your instrument to
this pitch, in place of a pitch pipe or an electric guitar tuner.

The Tuner currently knows the tunings for the four stringed
instruments that I play: guitar (standard tuning), ukulele
(standard C6 reentrant tuning for soprano, concert, or tenor),
ukulele-baritone (standard G6 tuning) and my "main ax" ukulele-low-g
(low-G-string linear C6) .  You can add your own tuning to
`tuner-tunings'.

The buffer shows the list of known tunings and you can "click" on one
to change the current set of pitches.  When switching, the open
strings are played in a single strum (you can turn off this frill
by customizing `tuner-play-tuning-when-switching').

Set your default instrument by customizing `tuner-default-tuning'.

Tuner requires one external program:
- play(1) from sox <https://sox.sourceforge.net/>
Errors from play are silently ignored.  If you don't hear the
tuning pitches or suspect other problems, invoke M-x tuner-debug-play.