Feature to be able to configure different number of records per page for subpanels

Currently admin can define global number of records per page in subpanels.
With a little modification to couple of core files we could allow configuration if this from subpanel definition, allowing developers to define their own sizes of subpanels.

Now in subpanel definition such as this yu can set records_per_page:
$layout_defs["my module"]["subpanel_setup"]['panel_name'] = array(
'order' => 10,
'sort_order' => 'desc',
'sort_by' => 'id',
'title_key' => 'LBL_TITLE',
'subpanel_name' => 'subpane_name',
'module'=>'my_module',
'get_subpanel_data' => 'function:get_my_magic_list',
'records_per_page' => 900,
'top_buttons' => array (),
);

of course 900 records per single subpanel page might be excessive... but if thats what someone wants then they can do it. This fix will not affect any old code whatsoever.