Change evaluation commands to bind nearest-repl/output-port to the

Change evaluation commands to bind nearest-repl/output-port to the
evaluation output port.  Eliminate variable transcript-value-truncate,
introduce new variables transcript-list-depth-limit and
transcript-list-breadth-limit, which default to #f.  Rename M-x
eval-definition to M-x eval-defun, and M-x eval-buffer to M-x
eval-current-buffer, both to match Emacs.