Issue #386 Notify prefix arg in mode-line with helm-M-x.
* helm-command.el (helm-M-x--notify-prefix-arg): new.
(helm-M-x): Run a timer to notify prefix-arg.
* helm.el (helm--mode-line-display-prefarg): New internal.
(helm-display-mode-line): allow notifying prefix arg, take one more arg 'force.