Added support for recording camera animation paths in osgGLUT::Viewer, and fixed

the osgGA::AnimationPathManipulator to handle it.

Added a new Drawable::ConstAttributeFunctor and make the accept(PrimitiveFunctor)
be a const method so can disallows modification.  Added Drawable::supports(...) methods
for each of the AttributeFunctor, ConstAttributeFunctor and PrimitiveFunctor so
that programs can querry whether it is possible to use functors with that object type.

src/osg/GeoSet.cpp

@@ -880,8 +880,32 @@ void GeoSet::accept(AttributeFunctor& auf)
     }
 }
 
+void GeoSet::accept(ConstAttributeFunctor& auf) const
+{
+    if (_numcoords == 0) computeNumVerts();
 
-void GeoSet::accept(PrimitiveFunctor& functor)
+    if (_coords && _numcoords)
+    {
+        auf.apply(VERTICES,_numcoords,_coords);
+    }
+    
+    if (_normals && _numnormals)
+    {
+        auf.apply(NORMALS,_numnormals,_normals);
+    }
+    
+    if (_colors && _numcolors)
+    {
+        auf.apply(COLORS,_numcolors,_colors);
+    }
+    
+    if (_tcoords && _numtcoords)
+    {
+        auf.apply(TEXTURE_COORDS_0,_numtcoords,_tcoords);
+    }
+}
+
+void GeoSet::accept(PrimitiveFunctor& functor) const
 {
     // will easily convert into a Geometry.