bug#46840: 27.1; Add gnus-draft-mode-prepared-hook

[積丹尼 Dan Jacobson]

If there were a gnus-draft-mode-prepared-hook, this could be simplified:
(add-hook
 'gnus-summary-prepared-hook ;gnus-draft-mode-hook won't work until second 
visit, so use:
 (lambda () ;No other way to start at the last article instead of the first.
   (if (string-match gnus-newsgroup-name "nndraft:drafts")
       (progn
         (goto-char (point-max))(forward-line -1))))); not the middle of the 
line, but good enough.

Also gnus-draft-mode-prepared-hook would sound clearer than
gnus-draft-prepared-hook, which seems like it is talking about a single draft.

P.S.,
(info "(gnus) Various Summary Stuff") mentions that mode's hooks, but
(info "(gnus) Drafts") doesn't. There are at least a couple.