(gnus-article-prepare-display): Bind `mime-display-text/plain-hook' to nil.

(gnus-article-prepare-display): Bind `mime-display-text/plain-hook' to nil.
(gnus-article-prepare-mime-display): Use `let' instead of `let*';
treat the next entity position as a marker.
(gnus-treatment-function-alist): Use `smiley-buffer' instead of
`gnus-smiley-display' under FSF Emacsen.
(gnus-treat-display-smileys): Default to t if the module `smiley-mule' is
installed.
(gnus-treat-display-xface): Default to `head' if the value of
`gnus-article-x-face-command' is `x-face-mule-gnus-article-display-x-face'.
(gnus-article-x-face-command): Default to
`x-face-mule-gnus-article-display-x-face' if the module `x-face-mule' is
installed.
(TopLevel): Require `static' first; require `path-util'.