Merge pull request ably#429 from ably/release/1.2.3

Release/1.2.3

Merge pull request ably#421 from ably/fix/216-basic-auth-refresh

Fix/216 basic auth refresh

Merge pull request ably#373 from ably/release/1.2.1

Release v1.2.1

Merge pull request ably#355 from ably/release/1.2.0

Release/1.2.0

Merge pull request ably#335 from ably/feature/rtn7-ack-nack

RTN7b: Handle ACK/NACK

Merge pull request ably#334 from ably/feature/330-unexport-iv

Unexport CipherParams.IV, useful only for tests

Merge pull request ably#280 from ably/bump-version

Bump the version constants

Merge pull request ably#265 from ably/reinstate-event-docs

Add examples for handling events and errors

Merge pull request ably#208 from ably/feature/rtl6c-queue-messages

RTL6c: Publish while not connected

Merge pull request ably#205 from ably/feature/pkg-level-func-options

Implement options as package-level functions