[CM] Snd 12.11

[Bill Schottstaedt]

Snd 12.11:

  s7: if WITH_SYSTEM_EXTRAS is 1 (default is 0) include
        directory? file-exists? delete-file getenv directory->list system
      with-baffle to limit the scope of continuations
      #_<name> is the initial (built-in, startup) value of <name>
      *error-info* replaced by error-environment, stacktrace changed slightly.
      hooks changed completely (s7 version bumped to 2.0 since this is a
        large backwards imcompatible change).
      procedure-setter is settable, so most of the old procedure-with-setter
        stuff is gone.
      s7_list, s7_environment_ref|set, s7_procedure_set_setter in s7.h.
      make-type replaced by open-environment. s7test.scm has a largely backwards
        compatible scheme version of make-type.
      aritable? to check arity match (named "procedure-arity-includes" in srfi-102).
      arity to generalize and replace procedure-arity
      removed trace and untrace (replaced by the trace macro in s7.html).
      I think these changes clean up most of the lingering ugly spots in s7!

  sndlib: removed mus-audio-describe, audinfo, ESD audio support.

  Snd: removed print-hook.

checked: sbcl 1.0.56, gtk 3.4.1|3.5.2, autoconf 2.69, ruby 1.9.3-p194, cairo 1.12.2
         gmp 5.0.5

Thanks!: Ludger Brummer, Torsten Anders, Mike Scholz, Rick Taube, Peter Bex.