title: insert text in the middle of string in flex 3
body: <p>can you please help me with this issue the String class does not have insert method it has only replace :( . </p>
  
  <p>what I need is:
  - if I have string "I stackoverflow" 
  - I need to insert "love " at index 2 to have "I love stackoverflow"</p>
  
  <p>so what I need is <strong>insertAt(index, String)</strong> </p>
  
  <p>thanks </p>