Order archive

*Title: Order archive

*Documentation:
This feature replaces the RemoveButton for the ArchiveButton in the order list
from the webshop. The archive functionality is added. The RemoveButton is
replaced because it gave the following problems: 

1. Removed IDs are reused. See bug number: 6623.
2. Payment gateways (Paynet) links to the deleted orders.
3. There is no way to keep the order list compact and clean, without deleting 
   orders.

The archive is the place where old processed or irrelevant orders should be
stored. The order list will be more compact and clean.

The ezorder table in the database has one new field: 
"is_archived int not null default 0". 

Set to 0 means that the order is not in the archive. If set to 1 the order is
archived. 

New templates:
shop/archivelist.tpl    - Show the archive overview. This is implemented for
                          the admin and standard design.

New module views:
shop/archivelist.php    - Overview of all archived orders.
shop/archiveorder.php   - Places an order to the archive (set archive state).
shop/unarchiveorder.php - Moves an order back to the order list (unarchive).