* add sender nickname in wxpusher ([5b238bf](https://github.com/msgbyte/tailchat/commit/5b238bf860d20bf4e99ead656a8083129bff16ef))
* add welcome plugin for user which can send welcome message when user join group ([dbebbc5](https://github.com/msgbyte/tailchat/commit/dbebbc54e66172653006a002c03b8932cb9d8ed2))
* **cli:** add smtp tools which help user positioning issue ([e357d2e](https://github.com/msgbyte/tailchat/commit/e357d2e1c56e4db376e2b1b29139581e4b32596d))
### Performance Improvements
* **admin-next:** optimize mongodb's performance on statistical quantities ([11154f7](https://github.com/msgbyte/tailchat/commit/11154f735b3ddbfcb33f4b6819ec78993e8a2044))