RawTextDescription works with nested lists

Syntax of nested lists:
  This is a nested list:
  + 1
  + + 1.1
  + + 1.2
  + + + 1.2.1
  + 2

Be careful, if you already used such symtax in some of your RawTextFields they have
to be updated (use save()) in order to make a call to the method that converts rawtext
to HTML code