lm_divider
Make a draggable frame divider.
            CALL:
            
         
   [hframe, jseparator] = lm_divider(hparent, varargin)
 
            INPUT:
            
         
    hparent:
      modelit.layout.Frame, the parent frame
    varargin:
      (property,value) pairs, valid properties:
      - rank: rank of frame, any number
      - tag:  tag of divider frame 
      - mode: resize mode, choose one of the following
              proportional: increase size of all lower frames
                            proportional at the cost of aall
                            above frame
              neighbour   : increase size of only next frame at
                            the cost of only the frame directly
                            above
 
            OUTPUT:
            
         
   hframe:
     modelit.layout.Divider
   jseparator:
     jacontrol of type jseparator