title: Editable value in Shiny selectizeInput
body: <p>I have a selectizeInput with X choices. My idea it should provide a sort of inputbox with X options but I want these choices to be editable. By this I mean if I select an option and I want edit part of it instead of being forced to click "backspace" or "delete" to clear the box, I want to be able to edit part of it. For example if I pick in the drop down box "New York" and I want to add "New Jersey", I should be able to pick "New York" and just replace the "York" with "Jersey" without the need to rewrite all the input.</p>
  
  <p>I can't seem to find any option to do this since the delete everything seems to be the default behaviour. </p>