Version 1.6.8 released.

Mosquitto 1.6.8 has been released, this is a bugfix release.

Broker

Various fixes for allow_zero_length_clientid config, where this option was not being set correctly. Closes #1429.
Fix incorrect memory tracking causing problems with memory_limit option. Closes #1437.
Fix subscription topics being limited to 200 characters instead of 200 hierarchy levels. Closes #1441.
Only a single CRL could be loaded at once. This has been fixed. Closes #1442.
Fix problems with reloading config when per_listener_settings was true. Closes #1459.
Fix retained messages with an expiry interval not being expired after being restored from persistence. Closes #1464.
Fix messages with an expiry interval being sent without an expiry interval property just before they were expired. Closes #1464.
Fix TLS Websockets clients not receiving messages after taking over a previous connection. Closes #1489.
Fix MQTT 3.1.1 clients using clean session false, or MQTT 5.0 clients using session-expiry-interval set to infinity never expiring, even when the global persistent_client_expiration option was set. Closes #1494.

Fix publish properties not being passed to on_message_v5() callback for QoS 2 messages. Closes #1432.
Fix documentation issues in mosquitto.h. Closes #1478.
Document mosquitto_connect_srv(). Closes #1499.

Fix duplicate cfg definition in rr_client. Closes #1453.
Fix mosquitto_pub -l hang when stdin stream ends. Closes #1448.
Fix mosquitto_pub -l not sending the final line of stdin if it does not end with a new line. Closes #1473.
Make documentation for mosquitto_pub -l match reality - blank lines are sent as empty messages. Closes #1474.
Free memory in mosquitto_sub when quiting without having made a successful connection. Closes #1513.

Added CLIENT_STATIC_LDADD to makefile builds to allow more libraries to be linked when compiling the clients with a static libmosquitto, as required for e.g. openssl on some systems.