*Title: best_sell_list extended fetch function

*Documentation:
Several new parameters were added to shop/best_sell_list fetch function to give
a possibility to fetch list of most sold products for a certain time duration.

*Usage:
fetch( 'shop', 'best_sell_list',
       hash( [ 'top_parent_node_id', parent_node_id, ]
             [ 'offset', offset, ]
             [ 'limit', limit, ]
             [ 'start_time', start_time, ]
             [ 'end_time', end_time, ]
             [ 'duration', duration, ]
             [ 'ascending', ascending, ]
             [ 'extended', extended, ]
              ) )

*Parameters:
Name:               Type:        Required:
 top_parent_node_id  integer      yes
 offset              integer      no
 limit               integer      no
 start_time          integer      no
 end_time            integer      no
 duration            integer      no
 ascending           boolean      no
 extended            boolean      no

*Example:

{def $best_sellers=fetch( 'shop', 'best_sell_list',
                          hash( 'top_parent_node_id', 2,
                                'limit', 5,
                                'offset', 0,
                                'start_time', maketime( 0, 0, 0 ),
                                'duration', mul( 60, 60, 24 ),
                                'extended', true() ) ) }

<table>
{foreach $best_sellers as $product}
    <tr>
    <td>{$product.object.name}
    <td>{$product.object.main_node.path_identification_string}
    <td>{$product.count}
    </tr>
{/foreach}
</table>
{undef}