reset orders as xml/api command

Add new xml command / api function to reset an order:
Order.reset()
<modify_order action="reset"/>

Resetting an order will have the following effect:

• If the order is not being processed by a job:
  The order is set to it's initial state, the next start is re-calculated using the run time

• If the order is currently being processed by a job:
  nothing will happen (the order will continue running depending on the job result)

• If the order is currently suspended:
  The order is set to it's initial state, the next start is re-calculated using the run time, the order is un-suspended

• If the order is currently set back:
  The order is set to it's initial state, the next start is re-calculated using the run time, the setback is cleared