Make return type from loadPagedModel explicit.

- explicitly return osg::PagedLOD instead of Node, so callers
don't need to rely on documentation + cast to get the LOD
settings on the result.

simgear/scene/model/modellib.cxx

@@ -152,7 +152,7 @@ SGModelLib::loadDeferredModel(const string &path, SGPropertyNode *prop_root,
     return proxyNode;
 }
 
-osg::Node*
+osg::PagedLOD*
 SGModelLib::loadPagedModel(const string &path, SGPropertyNode *prop_root,
                            SGModelData *data)
 {

simgear/scene/model/modellib.hxx

@@ -32,6 +32,10 @@
 #include <simgear/props/props.hxx>
 #include <simgear/misc/sg_path.hxx>
 
+namespace osg {
+    class PagedLOD;
+}
+
 namespace simgear {
 
 class SGModelData; // defined below
@@ -68,7 +72,7 @@ public:
     // the model file. Once the viewer steps onto that node the
     // model will be loaded. When the viewer does no longer reference this
     // node for a long time the node is unloaded again.
-    static osg::Node* loadPagedModel(const std::string &path,
+    static osg::PagedLOD* loadPagedModel(const std::string &path,
                                      SGPropertyNode *prop_root = NULL,
                                      SGModelData *data=0);