Update documentation for using SWIG_ConvertPtr example usage

Add a test case to test the example documentation typemaps

Examples/test-suite/python/typemap_documentation_runme.py

@@ -0,0 +1,20 @@
+import typemap_documentation
+
+f = typemap_documentation.Foo()
+f.x = 55
+b = typemap_documentation.Bar()
+b.y = 44
+
+if 55 != typemap_documentation.GrabVal(f):
+    raise RuntimeError("bad value")
+
+try:
+    typemap_documentation.GrabVal(b)
+    raise RuntimeError("unexpected exception")
+except TypeError:
+    pass
+
+if 55 != typemap_documentation.GrabValFooBar(f):
+    raise RuntimeError("bad f value")
+if 44 != typemap_documentation.GrabValFooBar(b):
+    raise RuntimeError("bad b value")