[CM] Snd 12.1

[Bill Schottstaedt]

Snd 12.1

  added lint.scm, a scheme lint checker.

  added expr.scm, which tries to find a math expression that matches
     an arbitrary set of data.

  added with-interrupts.  It defaults to #t, but both XtAppPending and 
     gtk_events_pending can cause a noticeable slow-down in the computation,
     so set with-interrupts to #f to turn off the GUI checks.

  added show-full-range to make the y-axis bounds accommodate the sound values.

  added info-popup-hook to specialize the popup menu's info output.

  removed verbose-cursor (use with-verbose-cursor).

  removed the unused "chn" parameter from the pan-mix functions in mix.scm.

checked: gtk 3.0.4|5|6|7|8, 3.1.2, sbcl 1.0.47, mpfr 3.0.1

Thanks!: Mike Scholz.