The spent command was tracked in a table flag, which is lost whenever the speed
table is rebuilt - the cell would go back to being a stop point. The memcell
already knows: StopCommandSent() drops the pending flag and keeps the text, so
the event now answers is_command_spent() and the table point follows it.
OrderNextGet() read one past the end of OrderList when the current order sat in
the last slot; it now reports Wait_for_orders there, which is what OrderNext()
wraps to anyway.