added support for sharing of extension_classes across modules

[SVN r8399]

shared_modules/m1.cpp

@@ -0,0 +1,28 @@
+#include "boost/python/module_builder.hpp"
+#include "boost/python/class_builder.hpp"
+#include "shared.hpp"
+#include "Python.h"
+
+struct M1 : Shared
+{
+    char const * name() const { return "M1"; }
+};
+
+namespace py = boost::python;
+
+char const * test(Shared const & m)
+{
+    return m.name();
+}
+
+extern "C" void initm1()
+{
+    py::module_builder m1("m1");
+    
+
+    py::class_builder<M1> m1_class(m1, "M1");
+    m1_class.def(py::constructor<>());
+    m1_class.declare_base(py::type<Shared>());
+    
+    m1.def(&test, "test");
+}