Support for MQTT v3.1.1 & missing callback fix

[avsdev-cw]

Have not run the tests, (have some issues running gtest for some reason... perhaps someone else could test?).

Whilst the header file states it supports v3.1.1, there are a few changes in the standards. Useful link: https://github.com/mqtt/mqtt.github.io/wiki/Differences-between-3.1.0-and-3.1.1

There is also a pdf you can download from oasis-open.org (quick google will lead you to it)

[mwallnoefer]

Commit 7f344f4 okay.

Regarding the second commit (f931a62) I am unsure if it is worth the effort, why not change directly to 3.1.1. I think that most libraries in the meantime should recognise it. There has also been filed a bug report about this: #60.

@emqtt/qmqtt-team Any proposal?

[mwallnoefer]

@emqplus Could you please comment on the second commit? Do we care about the difference between MQTT 3.1.0 and 3.1.1?

[mwallnoefer]

@avsdev-cw Is it possible to create a separate pull request just for the first commit (7f344f4) since I want to merge it?
For the second one we need to wait...

[avsdev-cw]

git/github isn't my preferred VCS, how would you like me to create the separate pull request?

[mwallnoefer]

You would need to create a new branch beside your own master branch in your forked repository (https://github.com/avsdev-cw/qmqtt) and put the single commit (7f344f4) there. This permits you to open a new pull request on that new branch.

In general it is better to propose one change (can also be multiple commits but on the same topic) at a time or work on different personal GIT branches and hence create multiple pull requests. So the maintainer is able to decide which ones to apply and which ones not.

I do not know how familiar you are with GIT, otherwise I will pull your changes manually. But the next time please follow my advice.