PubSub protocol support (#142)

* PubSub protocol support
Added support for :
- XEP-0050   (Command))
- XEP-0060   (PubSub)
- XEP-0004   (Forms)

Fixed the NewClient function by adding parsing of the domain from the JID if no domain is provided in transport config.
Updated xmpp_jukebox example

* Delete useless pubsub errors

* README.md update
Fixed import in echo example

* Typo

* Fixed raw send on client example

* Fixed jukebox example and added a README.md

stanza/msg_pubsub_event.go

@@ -0,0 +1,214 @@
+package stanza
+
+import (
+	"encoding/xml"
+)
+
+// Implementation of the http://jabber.org/protocol/pubsub#event namespace
+type PubSubEvent struct {
+	XMLName xml.Name `xml:"http://jabber.org/protocol/pubsub#event event"`
+	MsgExtension
+	EventElement EventElement
+	//List ItemsEvent
+}
+
+func init() {
+	TypeRegistry.MapExtension(PKTMessage, xml.Name{Space: "http://jabber.org/protocol/pubsub#event", Local: "event"}, PubSubEvent{})
+}
+
+type EventElement interface {
+	Name() string
+}
+
+// *********************
+// Collection
+// *********************
+
+const PubSubCollectionEventName = "Collection"
+
+type CollectionEvent struct {
+	AssocDisassoc AssocDisassoc
+	Node          string `xml:"node,attr,omitempty"`
+}
+
+func (c CollectionEvent) Name() string {
+	return PubSubCollectionEventName
+}
+
+// *********************
+// Associate/Disassociate
+// *********************
+type AssocDisassoc interface {
+	GetAssocDisassoc() string
+}
+
+// *********************
+// Associate
+// *********************
+const Assoc = "Associate"
+
+type AssociateEvent struct {
+	XMLName xml.Name `xml:"associate"`
+	Node    string   `xml:"node,attr"`
+}
+
+func (a *AssociateEvent) GetAssocDisassoc() string {
+	return Assoc
+}
+
+// *********************
+// Disassociate
+// *********************
+const Disassoc = "Disassociate"
+
+type DisassociateEvent struct {
+	XMLName xml.Name `xml:"disassociate"`
+	Node    string   `xml:"node,attr"`
+}
+
+func (e *DisassociateEvent) GetAssocDisassoc() string {
+	return Disassoc
+}
+
+// *********************
+// Configuration
+// *********************
+
+const PubSubConfigEventName = "Configuration"
+
+type ConfigurationEvent struct {
+	Node string `xml:"node,attr,omitempty"`
+	Form *Form
+}
+
+func (c ConfigurationEvent) Name() string {
+	return PubSubConfigEventName
+}
+
+// *********************
+// Delete
+// *********************
+const PubSubDeleteEventName = "Delete"
+
+type DeleteEvent struct {
+	Node     string         `xml:"node,attr"`
+	Redirect *RedirectEvent `xml:"redirect"`
+}
+
+func (c DeleteEvent) Name() string {
+	return PubSubConfigEventName
+}
+
+// *********************
+// Redirect
+// *********************
+type RedirectEvent struct {
+	URI string `xml:"uri,attr"`
+}
+
+// *********************
+// List
+// *********************
+
+const PubSubItemsEventName = "List"
+
+type ItemsEvent struct {
+	XMLName xml.Name      `xml:"items"`
+	Items   []ItemEvent   `xml:"item,omitempty"`
+	Node    string        `xml:"node,attr"`
+	Retract *RetractEvent `xml:"retract"`
+}
+
+type ItemEvent struct {
+	XMLName   xml.Name `xml:"item"`
+	Id        string   `xml:"id,attr,omitempty"`
+	Publisher string   `xml:"publisher,attr,omitempty"`
+	Any       *Node    `xml:",any"`
+}
+
+func (i ItemsEvent) Name() string {
+	return PubSubItemsEventName
+}
+
+// *********************
+// List
+// *********************
+
+type RetractEvent struct {
+	XMLName xml.Name `xml:"retract"`
+	ID      string   `xml:"node,attr"`
+}
+
+// *********************
+// Purge
+// *********************
+const PubSubPurgeEventName = "Purge"
+
+type PurgeEvent struct {
+	XMLName xml.Name `xml:"purge"`
+	Node    string   `xml:"node,attr"`
+}
+
+func (p PurgeEvent) Name() string {
+	return PubSubPurgeEventName
+}
+
+// *********************
+// Subscription
+// *********************
+const PubSubSubscriptionEventName = "Subscription"
+
+type SubscriptionEvent struct {
+	SubStatus string `xml:"subscription,attr,omitempty"`
+	Expiry    string `xml:"expiry,attr,omitempty"`
+	SubInfo   `xml:",omitempty"`
+}
+
+func (s SubscriptionEvent) Name() string {
+	return PubSubSubscriptionEventName
+}
+
+func (pse *PubSubEvent) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	pse.XMLName = start.Name
+	// decode inner elements
+	for {
+		t, err := d.Token()
+		if err != nil {
+			return err
+		}
+		var ee EventElement
+		switch tt := t.(type) {
+		case xml.StartElement:
+			switch tt.Name.Local {
+			case "collection":
+				ee = &CollectionEvent{}
+			case "configuration":
+				ee = &ConfigurationEvent{}
+			case "delete":
+				ee = &DeleteEvent{}
+			case "items":
+				ee = &ItemsEvent{}
+			case "purge":
+				ee = &PurgeEvent{}
+			case "subscription":
+				ee = &SubscriptionEvent{}
+			default:
+				ee = nil
+			}
+			// known child element found, decode it
+			if ee != nil {
+				err = d.DecodeElement(ee, &tt)
+				if err != nil {
+					return err
+				}
+				pse.EventElement = ee
+			}
+		case xml.EndElement:
+			if tt == start.End() {
+				return nil
+			}
+		}
+
+	}
+	return nil
+}