Added more comprehensive releaseGLObjects(State*=0) throughout Nodes,

Drawables,StateSet, and osgDB::Registry.

Added cleanup_frame() from to osgProducer::OsgCamerGroup to help with proper
clean of OpenGL objects before exit, and modified osgviewer, osghangglider,
osgwindows examples to do the extra frame call to cleanup_frame() before exit.

src/osg/Drawable.cpp

@@ -490,6 +490,8 @@ void Drawable::compileGLObjects(State& state) const
 
 void Drawable::releaseGLObjects(State* state) const
 {
+    if (_stateset.valid()) _stateset->releaseGLObjects(state);
+
     if (!_useDisplayList) return;
     
     if (state)

src/osg/Geode.cpp

@@ -214,3 +214,15 @@ void Geode::compileDrawables(State& state)
         (*itr)->compileGLObjects(state);
     }
 }
+
+void Geode::releaseGLObjects(osg::State* state) const
+{
+    Node::releaseGLObjects(state);
+
+    for(DrawableList::const_iterator itr=_drawables.begin();
+        itr!=_drawables.end();
+        ++itr)
+    {
+        (*itr)->releaseGLObjects(state);
+    }
+}

src/osg/Group.cpp

@@ -388,3 +388,15 @@ bool Group::computeBound() const
     _bsphere_computed = true;
     return true;
 }
+
+void Group::releaseGLObjects(osg::State* state) const
+{
+    Node::releaseGLObjects(state);
+
+    for(NodeList::const_iterator itr=_children.begin();
+        itr!=_children.end();
+        ++itr)
+    {
+        (*itr)->releaseGLObjects(state);
+    }
+}

src/osg/Node.cpp

@@ -427,3 +427,11 @@ void Node::dirtyBound()
 
     }
 }
+
+void Node::releaseGLObjects(osg::State* state) const
+{
+    if (_stateset.valid()) _stateset->releaseGLObjects(state);
+}
+
+
+