Let the activity system chose randomly what to do.

Side effect of returning self slave in slave list is used in SlapTool.

Narrow to only return Slave Instance related delivery lines.

Person shall have validated Open Order created. Empty one assuers, that nothing
is to do for given Person.

Confirmed Sale Order Line shall have Computer Partition.

Start at least *today* and if date is in day number higher then minimum amount
of days in month *rewind* and do not fast forward.

Store processed date.

Periodicity is known when service is available.

Add dates safely using DateUtils.
Round up start_date to next midnight.
In case if after rounding this date would go higher then minimum number of day
in month set it to next month beginning date.

Provide three parts:

 * desire to do (Person_storeOpenOrderJournal)
 * difference to apply (Person_getOpenOrderDifference)
 * apply (Person_updateOpenOrder)

It is possible to debug current state by using src__=1 parameter passed to
Person_storeOpenOrderJournal

Raise in case of bad state.

It is better to have few failing tests on check consistency and false positive
alarms then accidentally confirmed Sale Orders.

Support correctly stop date.
Postpone new open order creation on start date update, until update is needed.

It shall be extended always by one month.

Ordered orders can be without partition, but confirmed ones required it.
Also during confirmation check if partition was assigned correctly and
only then confirm order.