Websocket re-connect

[DarkCat09]

When connection is closed -- either cleanly (afaik currently it can happen only on logout) or by interrupt / ping timeout -- it's reasonable to try to reconnect. Current behavior is to fail silently on every method invocation because there's no error handling for websocket operations; also recv_loop just exits by websockets.exceptions.ConnectionClosedError.

[DarkCat09]

I can suggest two different ways to implement it:

• custom callback on socket error -- manual reconnection from developer's code
• automatic retrying -- when handling socket exception, call an internal function that retries reconnection with a specific delay until succeeded; in that case we also need to store a token we got after signing in

Combining these concepts by implementing the second one through a default reconnection callback feels like too much effort for a library with barely two users but i think it's the best solution

I'm ok with just a callback on my side

[DarkCat09]

Also: do we need to handle clean connection closing? I haven't seen it yet, probably only after logging out but i can't remember if MAX backend sends a Close packet in that case or websocket just timeouts too

Upd: decided to just exit from a receiver loop in case of clean closing, see 1948d85

[DarkCat09]

Partially solved in #21 (the approach with a custom callback)

[DarkCat09]

TODO: auto reconnection without the need to write a full callback on the app developer's side

This requires to rework our authorization flow and store an auth token in memory, i'll submit this in a separate PR