BUG/MINOR: spoe: Be sure to be able to quickly close IDLE applets on soft-stop

BUG/MINOR: spoe: Be sure to be able to quickly close IDLE applets on soft-stop

On soft-stop, we try, as far as possible, to process all pending messages
before closing SPOE applets. However, in sync mode, when an applets waiting
for a response receives the ACK frame, it is switched to IDLE state without
checking if it may be closed. In this case, we will wait the idle timeout
before closing de applet, delaying the soft-stop.

To reduce this delay, on soft-stop, IDLE applets are woken up. On the next
wakeup, the applet will try to process pending messages or will be
closed.

This patch should be backported to all stable versions.