Get Guile to be a little less chatty by default. The new user

Get Guile to be a little less chatty by default.  The new user
should see as little clutter as possible.
* r4rs.scm (%load-verbosely): Make this #f by default.
* boot-9.scm (scm-repl-verbose): Make this #f by default.
(scm-style-repl): Don't run 'pk' on the value passed to quit.

* r4rs.scm: New file.
* boot-9.scm: Load r4rs.scm, first thing.
(OPEN_READ, OPEN_WRITE, OPEN_BOTH, *null-device*, open-input-file,
open-output-file, open-io-file, close-input-port,
close-output-port, close-io-port, call-with-input-file,
call-with-output-file, with-input-from-port, with-output-to-port,
with-error-to-port, with-input-from-file, with-output-to-file,
with-error-to-file, with-input-from-string, with-output-to-string,
with-error-to-string, the-eof-object): Definitions moved to
r4rs.scm.  Not all of them are R4RS, but those that are use those
that are not.
(load, %load-verbosely, %load-announce): Moved, along with code to
set %load-hook, to r4rs.scm.