changelog

2020-10-20: 
    1. Added the move function using which one can move around in the viewing
       plane. To activate, press the right mouse button (left one for left-
       handed users) and drag the volume.  Also activated using arrow keys to 
       move up, down, left and right.  The size of the viewing area
       can be specified using the config option max_area_display_size in the 
       .yaml file. The default value for this parameter is 200. As the figure
       size is the same, in a way, this config option handles the amount 
       of zoom-in and zoom-out.  

    2. Moved sliders from bottom to the right and expanded the display figure a bit. 

        
2020-10-17:
    Several changes in this version: 
    1. The viewing axis can now be changed. The default viewing
       axis is Z. It can be changed using the new radio buttons on
       the right. Also, keyboard short- cuts 0, 1, 2 can be used to set
       the viewing axis to X, Y, and Z, respectively. The default 
       viewing axis is Z. 

    2. New sliders were added for X, Y, and Z planes. Changing
       the corresponding slider according to a viewing axis 
       will move through the planes.  Also, the sliders will maintain
       their values when the viewing axis is changed. Using the mouse wheel
       now moves the slider corresponding to the viewing axis. 

    3. A new scroll feature for the brush size was added. When the mouse
       is held over the brush size slider and moved down, the brush size is 
       incresed. It is decreased when the mouse wheel is moved up.