Pybotx

Added

* Sending and handling internal bot notifications.

Added

* Add method for retrieving list of bot's chats
* Add `inserted_at` field to `ChatFromSearch` model

Changed

* `HTTPRequest` & `HTTPResponse` moved to `clients.types`
* `HTTPRequest` now work with JSON (dict) instead of bytes. It improves consistency with
`HTTPResponse` and will be useful in interceptors implementation.
* Reply event field `source_chat_name` is optional now
* Forward event field `source_sync_id` is required now

Removed

* `HTTPResponse` bytes content property

Fixed

* `File` is now deleted when the message is updated
* `Bot_id` is now displayed in the request
* Add description for `BotXAPIError`

Added
* trusted issuers for request token verification

Added
* subscribe to unread counter in sending manifest
* ios and android fullscreen layout params for sending manifest

Added
* /api/v4/botx/smartapps/unread_counter support

Added
fields into UserFromSearch:

- created_at
- cts_id
- description
- ip_phone
- manager
- office
- other_ip_phone
- other_phone
- public_name
- rts_id
- update_at