incremental connection from client

[Mr-Tin-25]

1. connection a client to a server | StartClient();
2. stopping client connection | StopClient();
3. reconnect again || StartClient();

now client will be register twice.

doing 2. & 3. again will try to connect +1 each time.

Reason:
every time client gets started AddTransportHandlers() is call and callback are registered.
RemoveTransportHandlers() won't be triggered when client stops.
=> Callback are registered multiple times, that's why client connection increases.

[Helvest]

I have the same bug, in the last Mirror Update.

I found that the problem is from a missing call of "OnDisconnected?.Invoke();" in the the Disconnect() method in the class Client of Telepathy, when the client disconnect manually.

So I just added "OnDisconnected?.Invoke();" to the line 255 and it resolve the bug, at least for me.

[MrGadget1024]

@vis2k see also #3213

[miwarnec]

checking

[miwarnec]

let's close this in favor of #3213 , one open issue is enough