Peter M. Groen / FlashMQ

I think it's very hard to distinguish between protocol error and
malformed packet. It's kind of arbitrary...

Also fixes a bug in new interval calculation.

And the TODOs are for the next thing: saving the createdAt date.

This prevents bugs because the calling context forgets it. A (small)
downside is that I have to make the Publish argument non-const. But,
that's exactly what it is then, so...

Also fixed a length check bug.

Because clients can now also exist as dummy objects, I had to add some
extra checks.

Also split up handlePublish() and the new parsePublishData().

I'm not sure how I'm continueing. I need a safe point.

But, this is a safe point before I will refactor it. I will remove the
appStartTime and session last touched. With the new queued removals,
this is no longer necessary.

Not tested yet.

I'm simplying/merging the rec, comp and rel packets, but I'm not sure it will
work. Committing as a safe point.

Later: I got it done as planned. Testing qos > 0 and mqtt5 still needs
to be done more.

I think it's correct, but mosquitto_sub doesn't seem to support it, so I
can't test.

Also some other stuff I happen to see.

And one line about correlation data that was a bug.

I need to decide what to do with getPublishData

and that disabled test needs repurposing.

which also has implications on how I think to handle 'queuePacketAtSub'

The behavior for MQTT3 clients in the same, but I replaced the term
'clean session' and described the behavior in MQTT5 terms, of 'clean
start' and an expiry interval.

Most of it is limits we already implemented non-standard compliant.

For the coming MQTT5 support, I'll need this a lot.