/** @mainpage Marble 

Marble is an application that displays a view of the earth.  It is
both a valuable application in its own right, but also an example
program that shows how you can use the Marble widgets in your own
applications. 

We have designed Marble so that you can use its components easily to
enhance your application with geo services. This manual enumerates the
components and describes how to use them in your own application.

The Marble application makes use of the following classes and widgets:

1. MarbleWidget, the main widget in any application using the Marble
   framework.  This widget displays a view of the earth or any other
   globe, depending on which dataset is used.  The user can navigate
   the globe using either a control widget, e.g. the MarbleControlBox,
   or the mouse.  

2. MarbleModel, the data storage class that holds the data that is
   visualized in the MarbleWidget.  You can either create a
   MarbleModel of your own, or let the MarbleWidget create one for
   you. 

   This data model contains 3 separate datatypes: <b>tiles</b> which
   provide the background, <b>vectors</b> which provide things like
   country borders and coastlines and <b>placemarks</b> which can show
   points of interest, such as cities, mountain tops or the poles.

3. MarbleControlBox, the most advanced control widget for
   MarbleWidget. It can be used to navigate around the globe, zoom,
   search for placemarks like cities, control aspects of the view such
   as showing water bodies, ice, terrain types, and cities. It can
   also be used to control which dataset is used to provide the
   background for the image and the projection (currently globe and
   flat). 

These three classes provide the core of the classes that comprise the
Marble framework.  You can use only them and get a very capable
application if you just provide them with some good datasets.

In addition to this, there is also a simpler control widget called the
MarbleNavigator that only controls panning and zooming. The
MarbleNavigator is incorporated into the MarbleControlBox in the first
tab.  This control widget can be used in simpler application where
theming, searching and other advanced controls are not needed.

@see Marble::MarbleWidget
@see Marble::MarbleModel
@see MarbleControlBox
@see MarbleNavigator

 */