new events for video calling (#29)

* new events for video calling

* remove useless event

client_call_answer.go

@@ -0,0 +1,17 @@
+package tdproto
+
+// Signal server about answer
+type ClientCallAnswer struct {
+	BaseEvent
+	Params clientCallAnswerParams `json:"params"`
+}
+
+func (p ClientCallAnswer) GetName() string { return "client.call.answer" }
+
+type clientCallAnswerParams struct {
+	// Chat or contact id
+	Jid JID `json:"jid"`
+
+	// SDP (session description protocol) data
+	Sdp string `json:"sdp"`
+}

server_call_offer.go

@@ -0,0 +1,23 @@
+package tdproto
+
+// Signal client about offer
+type ServerCallOffer struct {
+	BaseEvent
+	Params serverCallOfferParams `json:"params"`
+}
+
+func (p ServerCallOffer) GetName() string { return "server.call.offer" }
+
+type serverCallOfferParams struct {
+	// Chat or contact id
+	Jid JID `json:"jid"`
+	// SDP (session description protocol) data
+	Sdp string `json:"sdp"`
+}
+
+func NewServerCallOffer(jid JID, sdp string) (r ServerCallOffer) {
+	r.Name = r.GetName()
+	r.Params.Jid = jid
+	r.Params.Sdp = sdp
+	return r
+}