* dynl.c, error.c, eval.c, feature.c, filesys.c, fports.c, list.c, load.c,

net_db.c, read.c, socket.c: Update error messages to use ~A for
%s, ~S for %S to work with new `simple-format' format and be
standardized better.

* print.h, print.c (scm_simple_format): Added `simple-format'
primitive.  It's the old scm_display_error, with ARGS now a rest
parameter, and the destination first instead of last (and a couple
new capabilities inspired by `format' -- #t as destination means
current-output-port, #f means return the formatted text as a
string.

* gh.h, gh_data.c, ports.h, ports.c: Added some missing const specifications.

* backtrace.c (scm_display_error_message): Rewrote to use
scm_simple_format() procedure.

* __scm.h: Added commented-out #define of GUILE_DEBUG_FREELIST

libguile/dynl.c

@@ -389,7 +389,7 @@ as the @var{lib} argument to the following functions.")
 	      flags &= ~DYNL_GLOBAL;
 	  }
 	else
-	  scm_misc_error (FUNC_NAME, "unknown keyword argument: %s",
+	  scm_misc_error (FUNC_NAME, "unknown keyword argument: ~A",
 			  scm_cons (kw, SCM_EOL));
       }