assert-repl-* and associated state variables to scm-style-repl

assert-repl-* and associated state variables to scm-style-repl

* module/ice-9/boot-9.scm:
* module/ice-9/scm-style-repl.scm (scm-repl-silent, assert-repl-silence)
  (scm-repl-print-unspecified, assert-repl-print-unspecified)
  (scm-repl-verbose, assert-repl-verbosity)
  (scm-repl-prompt): Move these definitions here from boot-9.scm.

* module/ice-9/deprecated.scm (assert-repl-silence):
  (assert-repl-print-unspecified, assert-repl-verbosity): Deprecated
  wrappers for the functions. I'm not sure if the variables can be
  helped though.