Doc update.

Don't close the wrong end of a channel. But if we get an error, we can close the underlying socket.

Initial roster contents look like a result iq.

Doc update.

Start reading from the recv channel earlier.

Simplified and debugged the filter logic.

Fixed another logic error, caused by a shadowed variable name.

Fixed some logic errors and initialized some things that needed to be initialized.

Removed some unused code.

Fixed reversed-logic error in checking for duplicate stanza extension types.

Address a bug that can happen if no SRV records can be found.

Pass the TLS config as a parameter to the Client constructor. Updated the example program.

Moved the tls.Config from a package-level variable to a client instance variable.

Use reflection instead of constructor functions to create extended stanza structures.

Renamed client.In and client.Out to Recv and Send, respectively.