Implement Close and fix reaper goroutine leak.

[vmihailenco]

@dim please review

Also do you any plans how to release v3 with latest API changes and Cluster client?

[dim]

You are not unlocking clientMx when c.closed on two occasions. Sometimes it's worth accepting the additional allocation and simply deferring the Unlock to improve code readability, I think

[dim]

I also think you should cache the ticker on the client instance and close(c.ticker.C) when closing the client to make sure the reaper goroutine doesn't linger around unnecessarily.

[vmihailenco]

@dim thanks, fixed. PTAL.

[vmihailenco]

PTAL

[dim]

Not a problem, just out of interest: what's the benefit of deferring the unlock before acquiring the lock? I've seen you doing it on a few occasions. Looks like no one else is doing it this way 'round.

[vmihailenco]

It should be slightly faster (I believe), because defer c.clientsMx.Unlock() is evaluated before the lock is acquired. It does not matter too much and I have to stop doing this.

[dim]

Cool, ship it! :)