Add testcase for nested inner class deriving from a templated base class and defined outside of the outer class.

For languages that don't support nested class support, use flatnested.
See issue #270

Examples/test-suite/python/nested_template_base_runme.py

@@ -0,0 +1,13 @@
+from nested_template_base import *
+
+
+ois = InnerS(123);
+oic = InnerC();
+
+# Check base method is available
+if (oic.outer(ois).val != 123):
+  raise RuntimeError("Wrong value calling outer");
+
+# Check non-derived class using base class
+if (oic.innerc().outer(ois).val != 123):
+  raise RuntimeError("Wrong value calling innerc");