* gnus-art.el (gnus-default-article-saver): Doc fix.
(gnus-article-save-coding-system): Move from gnus-sum.el, rename
from gnus-summary-save-article-coding-system, and default to a
certain coding system.
(gnus-output-to-file): Add coding cookie and encode text according
to gnus-article-save-coding-system; don't use mm-append-to-file.
* gnus-sum.el (gnus-summary-save-article-coding-system): Move to
gnus-art.el and rename to gnus-article-save-coding-system.
(gnus-summary-save-article): Require gnus-art; don't show all
headers if it decodes articles; don't add coding cookie here;
don't bind mm-text-coding-system-for-write.
(gnus-summary-save-article-file): Save decoded articles.
(gnus-summary-write-article-file): When saving many files, use
gnus-summary-write-to-file first and gnus-summary-save-in-file
thereafter unless gnus-prompt-before-saving is always.
(gnus-summary-save-article-body-file): Save decoded articles.
* lpath.el: Fbind select-safe-coding-system for XEmacs.