Implement greet inbox and outbox

- Add user_greet model and startup table sync
- Implement /greet/user and /greet/delete handlers
- Implement noticeFriendGreeting inbox and noticeUserGreetingHistory outbox
- Return peer profile and center unit info for greeting notices
- Update login topInfo friend greet counters from unread inbox messages

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/model/user/usergreet.go

@@ -0,0 +1,19 @@
+package usermodel
+
+const GreetingPageSize = 40
+
+type UserGreet struct {
+	NoticeID            int    `xorm:"notice_id pk autoincr"`
+	AffectorID          int    `xorm:"affector_id index"`
+	ReceiverID          int    `xorm:"receiver_id index"`
+	Message             string `xorm:"message text"`
+	Reply               bool   `xorm:"reply"`
+	Readed              bool   `xorm:"readed"`
+	DeletedFromAffector bool   `xorm:"deleted_from_affector"`
+	DeletedFromReceiver bool   `xorm:"deleted_from_receiver"`
+	InsertDate          int64  `xorm:"insert_date index"`
+}
+
+func (UserGreet) TableName() string {
+	return "user_greet"
+}