[FIXED] TLS read/write not correctly reporting connection as closed
[FIXED] TLS read/write not correctly reporting connection as closed

This is a regression introduced by implementation of WriteDeadline
in PR #268 (v2.1.0).
If a SSL read or write returns 0 for bytes read/written, the connection
should be reported as closed.

Resolves #415

Signed-off-by: Ivan Kozlovic <a15f8b81a160b4eebe5c84e9e3b65c87b9b2f18e@synadia.com>

nats-io/cnats,nats-io/cnats,nats-io/cnats