Tweak the default choose modes formats:

- Only show pane title if it is not default and not empty.
- Add a prettier time format and use that instead of long ctime().
- Remove clutter and change the order.

tmux.1

@@ -4353,6 +4353,10 @@ gives
 .Ql #{t:window_activity}
 gives
 .Ql Sun Oct 25 09:25:02 2015 .
+Adding
+.Ql p (
+.Ql `t/p` )
+will use shorter but less accurate time format for times in the past.
 The
 .Ql b:\&
 and