Add "permission" for sessions that may not receive display names.

By default, the "join" events contain the whole userdata as received
from the "auth" response. This might include a "displayname" field
containing the display name of the associated user.

For privacy reasons in certain scenarios, some attendees should not
be able to know which other users are connected to a room, therefore
the "displayname" should be hidden for them. By default, no filtering
occurrs.

api_signaling.go

@@ -620,6 +620,18 @@ type RoomFlagsServerMessage struct {
 	Flags     uint32 `json:"flags"`
 }
 
+type ChatComment map[string]interface{}
+
+type RoomEventMessageDataChat struct {
+	Comment *ChatComment `json:"comment,omitempty"`
+}
+
+type RoomEventMessageData struct {
+	Type string `json:"type"`
+
+	Chat *RoomEventMessageDataChat `json:"chat,omitempty"`
+}
+
 type EventServerMessage struct {
 	Target string `json:"target"`
 	Type   string `json:"type"`
@@ -646,6 +658,15 @@ type EventServerMessageSessionEntry struct {
 	RoomSessionId string           `json:"roomsessionid,omitempty"`
 }
 
+func (e *EventServerMessageSessionEntry) Clone() *EventServerMessageSessionEntry {
+	return &EventServerMessageSessionEntry{
+		SessionId:     e.SessionId,
+		UserId:        e.UserId,
+		User:          e.User,
+		RoomSessionId: e.RoomSessionId,
+	}
+}
+
 // MCU-related types
 
 type AnswerOfferMessage struct {