[Echo.StreamServer.API.WebSockets] handle use case when updating connection provided with error;
[WebSockets] proper way to clear events
Remove unnecessary code
[Echo.StreamServer.API] onOpen handler removed; unconditionally clearing subscriptions after stopping the live updates
[Echo.StreamServer.API] deferred live updates initialization (we need since parameter before starting); minor fixes;
[Echo.API.Transports.WebSocket] more proper machinery for cases close/error/disconnect;
[Echo.API.Transport] merge config before sending a request (backwards compat);
[Echo.StreamServer.Controls] revert checking of the requestType parameter;
[Tests] more tests for the WS
Merge branch 'rc3.0.12' into evseev/get-rid-of-appkey-in-canvas