Channel improvements

[Krzysztof-Cieslak]

• Adds type-safety to the Message in handle action
• Renames SocketInfo to ClientInfo
• Adds the whole bunch of documentation
• Mark SocketHub and SocketMiddleware classes as internal

[Krzysztof-Cieslak]

CC: @baronfel @robertpi @isaacabraham

[baronfel]

I like these changes a lot. Obviously docs are great, but the typed message handlers are nice as well. One thing that I see being challenging is people wanting to model channel messages as DUs and then running into deserialization errors.

[Krzysztof-Cieslak]

channel messages as DU

Well, it’s problem everywhere - in controllers, in normal http handlers. And it depends - channels are using same IJSonSerializer as any other feature so the behavior should be consistent

[robertpi]

Looks good to me, all I was doing was using the json serialize to deszeialize the message, so will save me a few lines.