changes to LibreCAD 3

@All,

in the goal to make the kernel Qt free I have removed almost all Qt classes from the kernel.
In return I added the following frameworks:

1) Nano signal slot (instad of CONNECT) : https://github.com/NoAvailableAlias/nano-signal-slot
2) Logging framework (instead of qDebug()) : http://logging.apache.org/log4cxx/

For all container classes we now use std::map, std::vector and friends.

At first I wanted to have a message bus instead of a signal/slot system but I couldn't find a suitable framework. Apparently this can be a hard subject specially when you want to create libraries. I think nano signal slot is very suitable for us and we can always visit a message bus later, the interfaces using c++11 look a lot alike...

The kernel is now Qt free!

Build has also been tested on linux mint.

Good luck guys, see you soon here in the forum.
Best regards
Claudio

Good luck Ries, I see you are making some progress, well done for your first hard work. Lets hope LibreCAD 3 will be with us soon.