avoid throwing if Mapnik 2.1 style <Parameters> is encountered in XML

CHANGELOG

@@ -13,6 +13,8 @@ For a complete change history, see the SVN log.
 Mapnik 2.0.2
 ------------
 
+- XML: Fixed to avoid throwing if a `<Parameters>` element is encountered (which is supported in >= 2.1.x)
+
 - Support for PostGIS 2.0 in the pgsql2sqlite command (e69c44e/47e5b3c)
 
 - Fixed reference counting of Py_None when returning null attributes from Postgres during UTFGrid encoding, which could cause a Fatal Python error: deallocating None (#1221)

src/load_map.cpp

@@ -389,6 +389,10 @@ void map_parser::parse_map_include( Map & map, ptree const & include )
             }
             datasource_templates_[name] = params;
         }
+        else if (v.first == "Parameters")
+        {
+            // do not throw in order to support Mapnik 2.1.x stylesheets
+        }
         else if (v.first != "<xmlcomment>" &&
                  v.first != "<xmlattr>")
         {