admin: move revoke message field in separate argument

admin.go

@@ -139,12 +139,14 @@ func Forever() int64 {
 }
 
 // Ban will ban user from chat until `member.RestrictedUntil`.
-func (b *Bot) Ban(chat *Chat, member *ChatMember) error {
+func (b *Bot) Ban(chat *Chat, member *ChatMember, revokeMessages ...bool) error {
 	params := map[string]string{
-		"chat_id":         chat.Recipient(),
-		"user_id":         member.User.Recipient(),
-		"until_date":      strconv.FormatInt(member.RestrictedUntil, 10),
-		"revoke_messages": strconv.FormatBool(member.RevokeMessages),
+		"chat_id":    chat.Recipient(),
+		"user_id":    member.User.Recipient(),
+		"until_date": strconv.FormatInt(member.RestrictedUntil, 10),
+	}
+	if len(revokeMessages) > 0 {
+		params["revoke_messages"] = strconv.FormatBool(revokeMessages[0])
 	}
 
 	_, err := b.Raw("kickChatMember", params)

chat.go

@@ -80,11 +80,10 @@ func (c *Chat) Recipient() string {
 type ChatMember struct {
 	Rights
 
-	User           *User        `json:"user"`
-	Role           MemberStatus `json:"status"`
-	Title          string       `json:"custom_title"`
-	Anonymous      bool         `json:"is_anonymous"`
-	RevokeMessages bool         `json:"revoke_messages"`
+	User      *User        `json:"user"`
+	Role      MemberStatus `json:"status"`
+	Title     string       `json:"custom_title"`
+	Anonymous bool         `json:"is_anonymous"`
 
 	// Date when restrictions will be lifted for the user, unix time.
 	//