Added new osgGA - GUI Adapter library submitted by Neil Salter. This will

replace the current GUI adapter code inside osgUtil.

src/osgGA/GUIEventHandler.cpp

@@ -0,0 +1,43 @@
+#include <osgGA/GUIEventHandler>
+
+using osgGA::CompositeGUIEventHandler;
+
+bool CompositeGUIEventHandler::handle(const GUIEventAdapter& ea,GUIActionAdapter& aa)
+{
+    bool result=false;
+
+    for (ChildList::iterator itr=_children.begin();
+         itr!=_children.end();
+         ++itr)
+    {
+        result |= (*itr)->handle(ea,aa);
+    }
+    return result;
+}
+
+
+bool CompositeGUIEventHandler::addChild(GUIEventHandler *child)
+{
+    if (child && !containsNode(child))
+    {
+        // note ref_ptr<> automatically handles incrementing child's reference count.
+        _children.push_back(child);
+        return true;
+    }
+    else return false;
+
+}
+
+bool CompositeGUIEventHandler::removeChild(GUIEventHandler *child)
+{
+    ChildList::iterator itr = findChild(child);
+    if (itr!=_children.end())
+    {
+        // note ref_ptr<> automatically handles decrementing child's reference count.
+        _children.erase(itr);
+
+        return true;
+    }
+    else return false;
+
+}