Fixed empty string crash in mosquitto_property_copy_all

Correct a wrong example

Fix comments errors, it is the client that sends PING to broker actively

Signed-off-by: Alexander Fiebig <alex.fiebig@online.de>

and hence unchanged values disappearing. Thanks to Wim Nelis and
Christoph Krey.

Merge branch 'x-forwarded-for-lws' of https://github.com/hardillb/mosquitto into hardillb-x-forwarded-for-lws

I know you've added this for the next release, but here is a fix
for LWS. But just incase there are any more 2.0.x releases.

It does leave the incoming port as 0 but as this is pretty meaningless
for a proxied connection I think it's probably ok.

Signed-off-by: Ben Hardill <hardillb@gmail.com>

Closes #2609. Thanks to JSchy65.

Currently only a single plugin can interact with a unique $CONTROL
topic. Using multiple instances of the plugin would produce duplicate
entries in the config file.

Closes #2601.
Closes #2470.

They will now not modify the client/group if a new group/client being
added is not valid, or on other failures.

Closes #2598. Thanks to Sebastian Szczepański.

Closes #2545. Thanks to p-luke.

This happens when local_cleansession is set to false and cleansession is
set to true.

Closes #2604. Thank to Frank Dekervel.

mosquitto_ctrl example for setClientId was provided with wrong example (duplicate of setClientPassword).

Issue #2463.

Closes #2520. Thanks to sezanzeb

This happens when a client is kicked in the dynamic security plugin.

Closes #2525. Thanks to sezanzeb.

Closes #2463. Thanks to Tim Nordell.

Closes #2471. Thanks to Vitaljok and rillbert