Peter M. Groen / FlashMQ

There were bugs in which authentication object was used when, causing
threadings bugs. Instead of getting from the 'sender', we can just store
a thread local pointer.

Files are simple serialized bytes prefaced by lengths. File is hashed to
verify integrity. This was also a good way preventing unexpected errors
when trying to crash the parser by having it load a different file.

This change includes some refactoring that was necessary:

- It 'fixes' looking at the wrong thread's authentiction. This is still
  wrong though. It will be fixed by a thread local pointer in the next
  commit.
- Deadlocks with yourself are handled in rwlockguard.
- QoSPacketQueue is now a class.
- Probably other tweaks.

It didn't clean up the old ones, causing unpredictable problems.

Three parts to it:

- Start the app fresh per test. This avoids annoyances like getting
  retained messages on subscribe, messing up the test.
- Waiting for suback was apparently necessary.
- Because the Qt event loop was given time, waiting for publishes was
  sometimes pointless because it had already arrived. So, checking the
  receive list first.

Also include a few stats.

Shifting signed integers is undefined and only sometimes produced
unexpected results.

Was detected in packet identifiers in QoS testing.

Instead of getting it from the sender of a packet. Sometimes there was
no sender.

This fixes a crash on retained messages, because those newly created
packets didn't have a sender to get the threaddata from. So, using a
special object for it is easier and more robust.

The MQTT docs showed a wrong condition for checking malformed packets.

And, we have to grow buffers to MAX_PACKET_SIZE, otherwise we can't
process. I still have some inteligent buffer shrink logic in mind.

There still is a bug: writing a very big packet. I wrote the test case
already.