Continued changes to pass environment to READ and WRITE where

Continued changes to pass environment to READ and WRITE where
possible.  Change interfaces of

	REPL-READ
	REPL-EVAL
	REPL-WRITE
	PROMPT-FOR-EXPRESSION
	PROMPT-FOR-COMMAND-EXPRESSION
	WRITE-RESULT

and their associated hooks/methods so that environment is passed
consistently, with more-or-less regular argument structures.
Implement new procedure REPL-EVAL/WRITE that combines REPL-EVAL and
REPL-WRITE, since that's a common combination.