Allow to ignore addresses when doing wide replies

Introduce a new variable, mu4e-compose-reply-ignore-address, which matches
addresses to be skipped when doing wide replies.

This is identical in behavior to messages-dont-reply-to-names from message.el
(which we default on).

mu4e/mu4e-draft.el

@@ -191,6 +191,30 @@ the list form the original."
       reply-to)))
 
 
+(defun mu4e~strip-ignored-addresses (addrs)
+  "Return all the addresses in ADDRS not matching
+`mu4e-compose-reply-ignore-address'."
+  (cond
+    ((null mu4e-compose-reply-ignore-address)
+      addrs)
+    ((functionp mu4e-compose-reply-ignore-address)
+      (remove-if
+	(lambda (elt)
+	  (funcall mu4e-compose-reply-ignore-address (cdr elt)))
+	addrs))
+    (t
+      ;; regexp or list of regexps
+      (let* ((regexp mu4e-compose-reply-ignore-address)
+	     (regexp (if (listp regexp)
+		       (mapconcat (lambda (elt) (concat "\\(" elt "\\)"))
+			 regexp "\\|")
+		       regexp)))
+	(remove-if
+	  (lambda (elt)
+	    (string-match regexp (cdr elt)))
+	  addrs)))))
+
+
 (defun mu4e~draft-create-cc-lst (origmsg reply-all)
   "Create a list of address for the Cc: in a new message, based on
 the original message ORIGMSG, and whether it's a reply-all."
@@ -211,6 +235,8 @@ the original message ORIGMSG, and whether it's a reply-all."
 		      (mu4e~draft-address-cell-equal cc-cell to-cell))
 		    (mu4e~draft-create-to-lst origmsg)))
 		cc-lst))
+	    ;; remove ignored addresses
+	    (cc-lst (mu4e~strip-ignored-addresses cc-lst))
 	    ;; finally, we need to remove ourselves from the cc-list
 	    ;; unless mu4e-compose-keep-self-cc is non-nil
 	    (cc-lst

mu4e/mu4e-vars.el

@@ -387,6 +387,18 @@ are needed for sorting the contacts."
   :type 'string
   :group 'mu4e-compose)
 
+(defcustom mu4e-compose-reply-ignore-address message-dont-reply-to-names
+  "Addresses to prune when doing wide replies.
+
+This can be a regexp matching the address, a list of regexps
+or a predicate function. A value of nil keeps all the addresses."
+  :type '(choice
+	   (const nil)
+	   function
+	   string
+	   (repeat string))
+  :group 'mu4e-compose)
+
 (defcustom mu4e-compose-reply-to-address nil
   "The Reply-To address (if this, for some reason, is not equal to
 the From: address.)"