title: Autocompletion with qcompleter for fragments in the middle of a word
body: <p>Is there an example available of a <code>QCompleter</code> subclass that will provide autocompletions for fragments that appear in the middle of words? </p>
  
  <p>eg: </p>
  
  <p>Suppose you have the <code>wordlist { "apple", "pear", "banana" }</code>.
  When the user types <code>'p'</code>, the suggested autocompletions should be <code>"apple"</code> and <code>"pear"</code>, but not banana (because <code>"apple"</code> and <code>"pear"</code> both contain <code>'p'</code>); 
  The default autocompletion will only suggest <code>"pear"</code>.</p>