Line-bot-sdk

- Support Unsend & Video play complete event (284)
- Support Limit upToRemainingQuota property (290)
- Support get bot info (301)
- Support Narrowcast Redelivery object (293)
- Support webhook setting APIs (300)
- Support Flex Message update 2 (303)
* feat: add Background model
* feat: support justifyContent and alignItem
* update: spacer has been discontinued
* feat: support background model
* test: remove Spacer test case & establish background test cases
- Support sticker message keywords (305)

New features

- Support icon-nickname-switch (248)
- Support LINE emoji in messages (255)
- Support Get user's language (256)
- Support get group summary, count and room count API (271, 272)
- Support emoji length and X-Line-Retry-key (270)
- Support python3.8
- Improve `handler.add` (259, 276)

See also [the milestone](https://github.com/line/line-bot-sdk-python/milestone/1?closed=1)

**New Features**
- Support [Narrowcast API](https://developers.line.biz/en/reference/messaging-api/#send-narrowcast-message) (241)
- Support [stickerResourceType property added to sticker message webhook event](https://developers.line.biz/en/reference/messaging-api/#wh-sticker) (229)
- Support [mode property added to webhook event](https://developers.line.biz/en/news/2019/12/17/mode-property-for-webhook/) (#233)

**New Features**

- Support [new Messaging API endpoints for friend statistics](https://developers.line.biz/en/reference/messaging-api/#get-message-event) (216)
- Change domain name for some APIs to api-data.line.me (221, 222)
- Update `LineBotApibroadcast` (223)
- `LineBotApibroadcast` returns `BroadcastResponse` object which contains `request_id` property
- Update `LineBotApiError` (218)
- new properties `request_id` and `headers`

**New Features**

- Support [Flex Message Update 1](https://developers.line.biz/en/news/2019/08/#flex-message-update-1-released-2019-08-28) (205)

**New Features**

- Support a new api endpoint for **Friend statistics** (198)

**Trivial fixes**

- Add `maxLines` field to `Text component` (192)