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.

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.

Encrypted version only.

My IDE didn't understand them for finding symbols, apparently.

For better IDE functionality, mostly.

This also adds configuration options for choosing what address to bind
to.

This allows creation of multiple listeners, with different protocols
and/or SSL certificates.

Related change: settings is now a class that is copyable and assignable,
and is done so to each thread on reload.

Semi-related fix: fix crash in quit when multiple threads initiated it.
This came to light when testing the auth plugin settings.

The ping/pong is actually untested at this point, because Paho (my test
client for now) doesn't do those. I wonder if any do, because MQTT
already has ping/pong.

And some side issues.

This includes a timer mechanism.

It also contains some related improvements that I needed:

* Show disconnect reason
* Fix the while condition for doing write() to avoid an unnecessary call
* Config reloading logic

In preparation for clean session and qos.

It can be defined in the config file, along with options.

I kind of need a config file parser first, so I'm going to make that.

I put the main app in a seperate class for it, because it was easier.