code: function progress( _line ){
  
      messages[ _line ].progress++;
  
      if( (messages[ _line ].progress + messages[ _line ].diff) > 0 ){
  
          messages[ _line ].progress = 0;
  
      }
  
  }
docs: Incremente progress or reset if done.
  
  @param (int) _line - Line index