message: XPath: Remove redundant calls from xml_node::select_nodes et al
  Instead of delegating to a method that just forwards the call to
  xpath_query call the relevant method directly.
diff: @@ -12600,7 +12600,7 @@ namespace pugi
  PUGI__FN xpath_node xml_node::select_node(const char_t* query, xpath_variable_set* variables) const
  {
  xpath_query q(query, variables);
  - return select_node(q);
  + return q.evaluate_node(*this);
  }
  PUGI__FN xpath_node xml_node::select_node(const xpath_query& query) const
  @@ -12611,7 +12611,7 @@ namespace pugi
  PUGI__FN xpath_node_set xml_node::select_nodes(const char_t* query, xpath_variable_set* variables) const
  {
  xpath_query q(query, variables);
  - return select_nodes(q);
  + return q.evaluate_node_set(*this);
  }
  PUGI__FN xpath_node_set xml_node::select_nodes(const xpath_query& query) const
  @@ -12622,7 +12622,7 @@ namespace pugi
  PUGI__FN xpath_node xml_node::select_single_node(const char_t* query, xpath_variable_set* variables) const
  {
  xpath_query q(query, variables);
  - return select_single_node(q);
  + return q.evaluate_node(*this);
  }
  PUGI__FN xpath_node xml_node::select_single_node(const xpath_query& query) const
  