title: jqgrid - change to custom sorting icos
body: <p>i am using jqgrid to present a grid ,
  i whould like to custom the sorting icons ,
  we have a CMS and the content (include the arrows ) is controled by our clients. 
  however i don't have a problem doing it either by CSS or by code(js). 
  currently i see fixed arrows that are presented ,and the only thing i could custom is the possion and the apperance (vertical /horizinal) .</p>
  
  <p>my needs : 
  1.sperate icons for asc and desc(that will be coustom images).
  2.present one icon each click (tougle between the icons )</p>
  
  <p>many thanks </p>