Massive updates

What's Changed

• Wechat plugin by @xbotter in #80
• Enable knowledge in chatbot. by @hchen2020 in #82
• update Wechat plugin by @xbotter in #83
• Fix IConversationCompletionHook by @hchen2020 in #85
• Some fixes. by @hchen2020 in #86

New Contributors

• @xbotter made their first contribution in #80

Full Changelog: v0.5...v0.6