title: map <S-TAB> to to tab key
body: <p>I'm using the vim plugin <a href="https://github.com/ervandew/supertab" rel="nofollow">supertab</a> to map the <code>&lt;TAB&gt;</code> key to autocompletion, I however, sometimes want the old tab functionality (to indent at the end of a word), and wanted to map it to <code>&lt;S-TAB&gt;</code>, but I can't seem to make it work.</p>
  
  <p>The documentation states there is <code>g:SuperTabMappingTabLiteral</code>, which I can set, to get the old tab functionality back. I set it to <code>let g:SuperTabMappingTabLiteral = '&lt;s-tab&gt;'</code> but that doesn't seem to work either.</p>
  
  <p>The other questions on SO are about how to get a literal tab character with supertab enabled, <strong>I don't want a literal tab</strong>.</p>