Updated app description.

Signed-off-by: Mike Schoonover <mike@skoonie.com>
The GUI controls are now placed in a separate panel controlsPanel so that
a second panel can easily be added later to the same mainPanel to separate
the controls from other display items.

Created method addVerticalSpacer to improve code readability.

Signed-off-by: Mike Schoonover <mike@skoonie.com>