Added osg::Identifer, osg::ValueMap and osg::ValueStack classes to provide a general purpose means for storing and retrieving values from map or stack containers.

Typical use will be for storing and passing values between nodes during traversals.

src/osg/ValueMap.cpp

@@ -0,0 +1,36 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
+ *
+ * This library is open source and may be redistributed and/or modified under
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * OpenSceneGraph Public License for more details.
+*/
+#include <osg/ValueStack>
+
+#include <stdlib.h>
+
+using namespace osg;
+
+ValueMap::ValueMap()
+{
+}
+
+ValueMap::ValueMap(const ValueMap& vm, const osg::CopyOp& copyop):
+    osg::Object(vm, copyop)
+{
+    for(KeyValueMap::const_iterator itr = vm._keyValueMap.begin();
+        itr != vm._keyValueMap.end();
+        ++itr)
+    {
+        _keyValueMap[itr->first] = osg::clone(itr->second.get(), copyop);
+    }
+}
+
+ValueMap::~ValueMap()
+{
+}