Synch up with main trunk with a little modification.

Synch up with main trunk with a little modification.

* wl-summary.el (wl-summary-make-number-list): Initialize.
(wl-summary-update-mark): New function.
(wl-summary-reply): Put `answered' mark on the message.
(wl-summary-reply): Set `number' argument to wl-draft-reply.

* wl-draft.el (wl-draft-parent-number): New buffer local variable.
(wl-draft-reply): Added optional argument `number';
Set wl-draft-parent-number.
(wl-draft-kill): Delete answered mark if it is a reply.