Peter M. Groen / FlashMQ

This required a special type WillPublish to make this easier and more
logical.

It erroneously referred to the system function 'dup' now...

Also fix some bugs:

- The password can be binary data.
- The will topic is now also checked.

This allows easier saving of MQTT5 properties, for which a new file
version for retained messages is created. It uses the packet parsing logic.

It went over boundry when there were no properties.

Also changed will logic in disconnect: only clear it when it's a
successful disconnect.

- Delay is properly counted from moment of disconnect.
- When a session is picked up again, the will is not sent.
- An actual fix to what I tried a few commits ago: fix sending will
  twice.

This logic should make storing wills also easier.

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.