+ reflect wkt_parser in python

```python

import mapnik
reader = mapnik.WKTReader()
geometry = reader.read("Point(123 123)")

```

bindings/python/mapnik_python.cpp

@@ -69,6 +69,7 @@ void export_view_transform();
 void export_raster_colorizer();
 void export_label_collision_detector();
 void export_logger();
+void export_wkt_reader();
 
 #include <mapnik/version.hpp>
 #include <mapnik/value_error.hpp>
@@ -479,6 +480,7 @@ BOOST_PYTHON_MODULE(_mapnik)
     export_raster_colorizer();
     export_label_collision_detector();
     export_logger();
+    export_wkt_reader();
 
     def("clear_cache", &clear_cache,
         "\n"