cleanup

Add support for boost::mem_fn to SGSharedPtr.

Remove a couple of "using" declarations from scene/model/model.hxx

simgear/scene/model/model.hxx

@@ -15,9 +15,6 @@
 #include <vector>
 #include <set>
 
-using std::vector;
-using std::set;
-
 #include <osg/Node>
 #include <osg/Texture2D>
 #include <osgDB/ReaderWriter>

simgear/structure/SGSharedPtr.hxx

@@ -111,4 +111,12 @@ private:
   friend class SGWeakPtr;
 };
 
+/**
+ * Support for boost::mem_fn
+ */
+template<typename T>
+T* get_pointer(SGSharedPtr<T> const & p)
+{
+  return p.ptr();
+}
 #endif