Added `decrease_total_clicks( id )` + call

Added `decrease_total_clicks( id )` + call

Added a function `decrease_total_clicks( id )` in js/insert.js which decreases the element containing the number of total clicks on the admin page by the value contained in the element `$('#clicks-' + id)` (i.e. by the value picked from the 'Clicks' column of the respective deleted row). Now called this method at the appropriate place in function `remove_link(id)`, thereby passing on `id` as parameter.