Add ibuffer-filter-by-derived-mode to ibuffer menu and doc

* lisp/ibuffer.el (ibuffer-mode-map, ibuffer-mode):
Add ibuffer-filter-by-derived-mode.

* etc/NEWS: Related markup.

etc/NEWS

@@ -453,6 +453,7 @@ The option `follow-intercept-processes' has been removed.
 specifying URL types that should be converted to remote file names at
 the FFAP prompt.  The default is now '("ftp").
 
+---
 ** New Ibuffer `derived-mode' filter, bound to `/ M'.
 The old binding for `/ M' (filter by used-mode) is now bound to `/ m'.
 

lisp/ChangeLog

 2012-11-11  Glenn Morris  <rgm@gnu.org>
+	* ibuffer.el (ibuffer-mode-map, ibuffer-mode):
+	Add ibuffer-filter-by-derived-mode.
+
 	* ibuffer.el (ibuffer-mode-map): Don't have two menu items with
 	the same name shadowing each other.

lisp/ibuffer.el

@@ -636,6 +636,9 @@ directory, like `default-directory'."
     (define-key-after map [menu-bar view filter filter-by-used-mode]
       '(menu-item "Add filter by a major mode in use..."
         ibuffer-filter-by-used-mode))
+    (define-key-after map [menu-bar view filter filter-by-derived-mode]
+      '(menu-item "Add filter by derived mode..."
+                  ibuffer-filter-by-derived-mode))
     (define-key-after map [menu-bar view filter filter-by-name]
       '(menu-item "Add filter by buffer name..." ibuffer-filter-by-name))
     (define-key-after map [menu-bar view filter filter-by-filename]
@@ -2438,8 +2441,9 @@ Marking commands:
 
 Filtering commands:
 
-  '\\[ibuffer-filter-by-mode]' - Add a filter by major mode.
-  '\\[ibuffer-filter-by-used-mode]' - Add a filter by major mode now in use.
+  '\\[ibuffer-filter-by-mode]' - Add a filter by any major mode.
+  '\\[ibuffer-filter-by-used-mode]' - Add a filter by a major mode now in use.
+  '\\[ibuffer-filter-by-derived-mode]' - Add a filter by derived mode.
   '\\[ibuffer-filter-by-name]' - Add a filter by buffer name.
   '\\[ibuffer-filter-by-content]' - Add a filter by buffer content.
   '\\[ibuffer-filter-by-filename]' - Add a filter by filename.