Default behaviour for v5 clients using `-c` is now to use infinite length
sessions, as with v3 clients.

Closes #1546. Thanks to Kiran Pradeep.

This allows the session-expiry-interval property to be easily set for
MQTT v5 clients.

Closes #1526. Thanks to Felix Moessbauer.

Closes #1520.

Conflicts:
	ChangeLog.txt
	config.mk
	src/context.c
	src/loop.c
	src/subs.c
	test/broker/01-connect-bad-packet.py
	test/broker/02-subpub-qos1-bad-pubcomp.py
	test/broker/02-subpub-qos1-bad-pubrec.py
	test/broker/02-subpub-qos2-bad-puback-1.py
	test/broker/02-subpub-qos2-bad-puback-2.py
	test/broker/02-subpub-qos2-bad-pubcomp.py
	test/broker/02-subpub-qos2.py
	test/broker/07-will-null-topic.py

Closes #1513.

In sub_client.c, call mosquitto_destroy() in cleanup label.

This is all now handled in session_expiry.c, through session expiry interval/time.

Closes #1494. Thanks to Christoph Krey.

Fixes: #1513 and frees resources when someone terminates
via SIGTERM or SIGINT.

Signed-off-by: Basavesh Shivakumar <basavesh.shivakumar@gmail.com>

Closes #1499. Thanks to Basavesh Shivakumar.

Signed-off-by: Basavesh Shivakumar <basavesh.shivakumar@gmail.com>

Blank lines are sent as empty messages.

Closes #1474. Thanks to majekw.

This would happen if the final line did not end with a new line.

Closes #1473. Thanks to majekw.

This allows outgoing messages from a bridge to have the retain bit
completely disabled, which is useful when bridging to e.g. Amazon or
Google.

It will not set the retain bit if retain-available is false.

This can occurs after one client takes over a previous connection.

Closes #1489. Thanks to Bas Verhoeven.

Install pkg-config files into arch dependent locations also for CMake builds

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

Closes #1371. Thanks to Fabrice Fontaine.

This seems to be required just on more modern Python versions.

Signed-off-by: Mario Vejlupek <mario@vejlupek.cz>