This feature is not in the core of Vanilla, but you can add it with a plugin:

  * [[http://lussumo.com/addons/?PostBackAction=AddOn&AddOnID=16|Quotations 1.5]] by [[http://lussumo.com/community/account/503/|Bergamot]]
  * or [[http://lussumo.com/addons/?PostBackAction=AddOn&AddOnID=18|QuoteText 1.0]] by [[http://lussumo.com/community/account/1290/|Jazzman]]