mu4e-view: use <mouse-2> for links

Only <mouse-2>, to be consistent with eww.

NEWS.org

@@ -171,6 +171,9 @@
       retrieval command in a buffer =*mu4e-last-update*=, = which can be useful
       for diagnosis.
 
+    - links (in text-mode emails) are now clickable through <mouse-2>, to be
+      consistent with eww.
+
     - support new-mail notifications on MacOS out-of-the-box
 
     - allow sorting by tag

mu4e/mu4e-view.el

@@ -431,11 +431,10 @@ list."
 
 (defvar mu4e-view-active-urls-keymap
   (let ((map (make-sparse-keymap)))
-    (define-key map [down-mouse-1] 'mu4e--view-browse-url-from-binding)
-    (define-key map [mouse-1] 'mu4e--view-browse-url-from-binding)
-    (define-key map (kbd "M-<return>") 'mu4e--view-browse-url-from-binding)
+    (define-key map (kbd "<mouse-2>")  #'mu4e--view-browse-url-from-binding)
+    (define-key map (kbd "M-<return>") #'mu4e--view-browse-url-from-binding)
     map)
-  "Keymap used for the urls inside the body.")
+  "Keymap used for the URLs inside the body.")
 
 (defvar mu4e--view-beginning-of-url-regexp
   "https?\\://\\|mailto:"

mu4e/mu4e.texi

@@ -1400,7 +1400,7 @@ E            edit (only allowed for draft messages)
 actions
 -------
 g            go to (visit) numbered URL (using `browse-url')
-(or: <mouse-1> or M-RET with point on url)
+(or: <mouse-2> or M-RET with point on URL)
 C-u g visits multiple URLs
 f            fetch (download )the numbered URL.
 C-u f fetches multiple URLs