add operator!= for GeoDataLatLonBox
have TextureLayer invalidate itself when visible LatLonBox changes (rather than relying on MarbleMap)
request repaint when TextureLayer changes
have TextureLayer invalidate itself when property value changes (rather than relying on MarbleMap)
fix crash in RoutingWidget

BUG: 321489
RoutingWidget: properly reset point selection state when point selection is finished or cancelled
implement input handling for point selection in RoutingWidget rather than in RoutingLayer

* frees the RoutingLayer from point selection logic
* concentrates point selection logic in RoutingWidget
foo
Revert "foo2"

This reverts commit a3d3f103eb331f839f6d4505afa1b492b6e1ee15.
introduce MarbleView
introduce MarbleGLView
introcude GlLayerInterface
clear depth buffer between layer rendering
TextureLayer
PlacemarkLayer
introduce triangulation algorithm for polygons

* taken from http://www.crystalspace3d.org/svnroot/crystal/CS/trunk/{include/csgeom/triangulate.h, libs/csgeom/triangulate.cpp}.
GeometryLayer
introduce GeoGraphicsScene::GlTile and use glDrawElements
adapt PlacemarkLayout
use shaders