Add XML payload support

Fixes #238

vendor/github.com/clbanning/mxj/struct.go

@@ -0,0 +1,54 @@
+// Copyright 2012-2017 Charles Banning. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file
+
+package mxj
+
+import (
+	"encoding/json"
+	"errors"
+	"reflect"
+
+	// "github.com/fatih/structs"
+)
+
+// Create a new Map value from a structure.  Error returned if argument is not a structure.
+// Only public structure fields are decoded in the Map value. See github.com/fatih/structs#Map
+// for handling of "structs" tags.
+
+// DEPRECATED - import github.com/fatih/structs and cast result of structs.Map to mxj.Map.
+//	import "github.com/fatih/structs"
+//	...
+//	   sm, err := structs.Map(<some struct>)
+//	   if err != nil {
+//	      // handle error
+//	   }
+//	   m := mxj.Map(sm)
+// Alernatively uncomment the old source and import in struct.go.
+func NewMapStruct(structVal interface{}) (Map, error) {
+	return nil, errors.New("deprecated - see package documentation")
+	/*
+		if !structs.IsStruct(structVal) {
+			return nil, errors.New("NewMapStruct() error: argument is not type Struct")
+		}
+		return structs.Map(structVal), nil
+	*/
+}
+
+// Marshal a map[string]interface{} into a structure referenced by 'structPtr'. Error returned
+// if argument is not a pointer or if json.Unmarshal returns an error.
+//	json.Unmarshal structure encoding rules are followed to encode public structure fields.
+func (mv Map) Struct(structPtr interface{}) error {
+	// should check that we're getting a pointer.
+	if reflect.ValueOf(structPtr).Kind() != reflect.Ptr {
+		return errors.New("mv.Struct() error: argument is not type Ptr")
+	}
+
+	m := map[string]interface{}(mv)
+	j, err := json.Marshal(m)
+	if err != nil {
+		return err
+	}
+
+	return json.Unmarshal(j, structPtr)
+}