* module/ice-9/safe-r5rs.scm: Define local versions of `case' and `cond'
that assume aux syntax is unbound. If this doesn't work, we can
switch to exporting aux syntax.
* module/ice-9/top-repl.scm (top-repl): Don't add (ice-9 r5rs) to the
REPL environment.
* module/ice-9/boot-9.scm (current-language): New parameter.
* module/system/base/language.scm (*current-language*): Pull fluid from
parameter.
(current-language): Now a re-exported parameter.
* doc/ref/compiler.texi: Update reference from *current-language* fluid
to current-language parameter.
* module/system/base/compile.scm (compile-and-load):
* module/ice-9/top-repl.scm (top-repl): Default to the current language,
not to Scheme.
* module/ice-9/eval-string.scm:
* module/system/base/language.scm:
* module/system/repl/command.scm:
* module/system/repl/repl.scm: Update to use current-language parameter
and parameterize.
* module/ice-9/debug.scm: Gut, though we keep the module around for code
Out There that uses it.
* module/ice-9/top-repl.scm (top-repl): Don't import (ice-9 debug)
* module/ice-9/debugger/commands.scm:
* module/ice-9/debugging/trace.scm:
* module/ice-9/emacs.scm: Remove ice-9 debug includes.
