Change Gnus hash tables into real hash tables

Gnus has used obarrays as makeshift hash tables for groups: group
names are coerced to unibyte and interned in custom obarrays, and
their symbol-value set to whatever value needs to be stored. This
patch replaces those obarrays with actual hash tables.

* lisp/gnus/gnus-util.el (gnus-intern-safe, gnus-create-hash-size):
  Remove functions.
  (gnus-make-hashtable): Change to return a real hash table.
  (gnus-text-property-search): Utility similar to `text-property-any',
  but compares on `equal'. Needed because the 'gnus-group text
  property is now a string.
* lisp/gnus/gnus.el (gnus-gethash, gnus-gethash-safe, gnus-sethash):
  Remove macros.
  (gnus-group-list): New variable holding all group names as an
  ordered list. Used because `gnus-newsrc-hashtb' used to preserve
  `gnus-newsrc-alist' ordering, but now doesn't.
* lisp/gnus/nnmaildir.el (nnmaildir--servers): Change from obarray to
  alist.
  (nnmaildir--up2-1): Remove function.
* lisp/thingatpt.el (thing-at-point-newsgroup-p): This was making use
  of Gnus obarrays, replace with a cond that can handle many different
  possibilities.
* lisp/gnus/gnus-bcklg.el (gnus-backlog-articles): Remove
  gnus-backlog-hashtb, which wasn't doing anything. Just keep a list
  of ident strings in gnus-backlog-articles.
  (gnus-backlog-setup): Delete unnecessary function.
  (gnus-backlog-enter-article, gnus-backlog-remove-oldest-article,
  gnus-backlog-remove-article, gnus-backlog-request-article): Alter
  calls accordingly.
* lisp/gnus/gnus-dup.el (gnus-duplicate-list-max-length): Rename from
  `gnus-duplicate-list-length', for accuracy.
* lisp/gnus/gnus-start.el (gnus-active-to-gnus-format,
  gnus-groups-to-gnus-format, gnus-newsrc-to-gnus-format): Read group
  names as strings.
  (gnus-gnus-to-quick-newsrc-format): Write `gnus-newsrc-alist' using
  the ordering in `gnus-group-list'.
* lisp/gnus/gnus-agent.el:
* lisp/gnus/gnus-async.el:
* lisp/gnus/gnus-cache.el:
* lisp/gnus/gnus-group.el:
* lisp/gnus/gnus-score.el:
* lisp/gnus/gnus-sum.el:
* lisp/gnus/gnus-topic.el:
* lisp/gnus/message.el:
* lisp/gnus/mml.el:
* lisp/gnus/nnagent.el:
* lisp/gnus/nnbabyl.el:
* lisp/gnus/nnvirtual.el:
* lisp/gnus/nnweb.el: In all files, change obarrays to hash-tables,
  and swap `gnus-sethash' for `puthash', `gnus-gethash' for `gethash',
  `mapatoms' for `maphash', etc.
* test/lisp/gnus/gnus-test-headers.el (gnus-headers-make-dependency-table,
  gnus-headers-loop-dependencies): New tests to make sure we're
  building `gnus-newsgroup-dependencies' correctly.

lisp/gnus/gnus-score.el

@@ -2234,8 +2234,7 @@ score in `gnus-newsgroup-scored' by SCORE."
 	  (let* ((score (or (nth 1 kill) gnus-score-interactive-default-score))
 		 (date (nth 2 kill))
 		 found)
-	    (when (setq arts (intern-soft (nth 0 kill) hashtb))
-	      (setq arts (symbol-value arts))
+	    (when (setq arts (gethash (nth 0 kill) hashtb))
 	      (setq found t)
 	      (if trace
 		  (while (setq art (pop arts))
@@ -2273,11 +2272,11 @@ score in `gnus-newsgroup-scored' by SCORE."
     (with-syntax-table gnus-adaptive-word-syntax-table
       (while (re-search-forward "\\b\\w+\\b" nil t)
 	(setq val
-	      (gnus-gethash
+	      (gethash
 	       (setq word (downcase (buffer-substring
 				     (match-beginning 0) (match-end 0))))
 	       hashtb))
-	(gnus-sethash
+	(puthash
 	 word
 	 (append (get-text-property (point-at-eol) 'articles) val)
 	 hashtb)))
@@ -2289,7 +2288,7 @@ score in `gnus-newsgroup-scored' by SCORE."
 				"."))
 			   gnus-default-ignored-adaptive-words)))
       (while ignored
-	(gnus-sethash (pop ignored) nil hashtb)))))
+	(remhash (pop ignored) hashtb)))))
 
 (defun gnus-score-string< (a1 a2)
   ;; Compare headers in articles A2 and A2.
@@ -2400,8 +2399,8 @@ score in `gnus-newsgroup-scored' by SCORE."
 		(goto-char (point-min))
 		(while (re-search-forward "\\b\\w+\\b" nil t)
 		  ;; Put the word and score into the hashtb.
-		  (setq val (gnus-gethash (setq word (match-string 0))
-					  hashtb))
+		  (setq val (gethash (setq word (match-string 0))
+				     hashtb))
 		  (when (or (not gnus-adaptive-word-length-limit)
 			    (> (length word)
 			       gnus-adaptive-word-length-limit))
@@ -2409,7 +2408,7 @@ score in `gnus-newsgroup-scored' by SCORE."
 		    (if (and gnus-adaptive-word-minimum
 			     (< val gnus-adaptive-word-minimum))
 			(setq val gnus-adaptive-word-minimum))
-		    (gnus-sethash word val hashtb)))
+		    (puthash word val hashtb)))
 		(erase-buffer))))
 	  ;; Make all the ignorable words ignored.
 	  (let ((ignored (append gnus-ignored-adaptive-words
@@ -2420,16 +2419,14 @@ score in `gnus-newsgroup-scored' by SCORE."
 				      "."))
 				 gnus-default-ignored-adaptive-words)))
 	    (while ignored
-	      (gnus-sethash (pop ignored) nil hashtb)))
+	      (remhash (pop ignored) hashtb)))
 	  ;; Now we have all the words and scores, so we
 	  ;; add these rules to the ADAPT file.
 	  (set-buffer gnus-summary-buffer)
-	  (mapatoms
-	   (lambda (word)
-	     (when (symbol-value word)
-	       (gnus-summary-score-entry
-		"subject" (symbol-name word) 'w (symbol-value word)
-		date nil t)))
+	  (maphash
+	   (lambda (word val)
+	     (gnus-summary-score-entry
+	      "subject" word 'w val date nil t))
 	   hashtb))))))
 
 (defun gnus-score-edit-done ()