context: add chat member updates

bot.go

@@ -245,6 +245,8 @@ func (b *Bot) NewContext(upd Update) Context {
 		preCheckoutQuery: upd.PreCheckoutQuery,
 		poll:             upd.Poll,
 		pollAnswer:       upd.PollAnswer,
+		myChatMember:     upd.MyChatMember,
+		chatMember:       upd.ChatMember,
 	}
 }
 

context.go

@@ -38,6 +38,12 @@ type Context interface {
 	// PollAnswer returns stored poll answer if such presented.
 	PollAnswer() *PollAnswer
 
+	// MyChatMember returns bot's chat member changes.
+	MyChatMember() *ChatMemberUpdated
+
+	// ChatMember returns chat member's changes.
+	ChatMember() *ChatMemberUpdated
+
 	// Migration returns both migration from and to chat IDs.
 	Migration() (int64, int64)
 
@@ -149,6 +155,8 @@ type nativeContext struct {
 	preCheckoutQuery *PreCheckoutQuery
 	poll             *Poll
 	pollAnswer       *PollAnswer
+	myChatMember     *ChatMemberUpdated
+	chatMember       *ChatMemberUpdated
 
 	lock  sync.RWMutex
 	store map[string]interface{}
@@ -193,6 +201,14 @@ func (c *nativeContext) PollAnswer() *PollAnswer {
 	return c.pollAnswer
 }
 
+func (c *nativeContext) MyChatMember() *ChatMemberUpdated {
+	return c.myChatMember
+}
+
+func (c *nativeContext) ChatMember() *ChatMemberUpdated {
+	return c.chatMember
+}
+
 func (c *nativeContext) Migration() (int64, int64) {
 	return c.message.MigrateFrom, c.message.MigrateTo
 }