title: Magento changing attribute type in backend
body: <p>is it possible to change type of a attribute after it has been created.
  I want to change type of certain attribute to Multi select list. Type of these attribute is currently 'Dropdown'. 
  Actually When I create the attributes, there was  no need of multi select when I created it originally, but, now client wants to change it to "Multi select".</p>
  
  <p>Please help me out, I can not create new attributes by deleting the old ones, as, there is some data, and certain part of design is hard coded and depends on certain values of attribute.</p>