Title: Status on orders

Documentation:
The order list has been enhanced by giving it the possibility to set a status per
order. This allows the shop owner to clearly state what is going on with an
order.

The system comes with 3 pre-defined statues named:
1 - Pending - The order has just been created and is not handled by a person yet.
2 - Processing - The order is currently being handled, this could mean that a person is assembling the parts.
3 - Delivered - The order is delivered to the end-user, e.g. sent by snail mail.

It is also possible for the site administrator to create more statuses, they are
known as custom statuses and will start at ID 1000 and increase from that.

Also a special status is defined, the status Undefined (value 0), this is used for
statuses that have been removed.

A status element consists of:
- status_id - A unique ID for the status, IDs lower than 1000 are internal ones.
- name - A describing name for the status
- is_active - Whether the status can be used or not, if false it will not be
              shown in drop-down lists.

In the permission system two new access functions have been added, they are:
shop/setstatus - Defines which status a user can set, also optionally which status
                 the order must originally have to be modified.
shop/edit_status - Controls if a user can edit/remove status items or not.

New templates:
shop/status.tpl - Controls the interface for editing, creating and removing statuses.
                  Implemented for admin and standard design.

New module views:
shop/status - Handles status elements, uses shop/status.tpl
shop/setstatus - View to change the status of an order.

New fetch functions:
shop/order_status_history_count - Returns the number of history elements for a given order ID
shop/order_status_history - Returns the status history elements for a given order ID