Remove `cl' requirement. Clean up whitespace.

Remove `cl' requirement.  Clean up whitespace.
Replace '?\ ' by '?\s' throughout.
(tutorial-warning-face): Inherit font-lock-warning-face.  Move to
`help' custom group.
(tutorial--key-description): New function.
(tutorial--display-changes): Remove redundant arg.  Scan for all
key sequences to avoid false matches.  Cleanup.
(tutorial--saved-dir): Save to a subdirectory in .emacs.d to
reduce homedir pollution.
(help-with-tutorial): Call tutorial--display-changes with no arg.