Get rid of Qt

[dbogdanov]

The reasons behind its use in Gaia were:

• QString that manages Unicode. There's hardly any alternatives to do that in C++ with a simple API.
• QMap and QVector are more easy to use that std C++, although the difference is small.
• Versioned QDataStreams made it easy to load and save datasets with different versions.
• Some more reasons we forgot...

Re-factor Gaia to get rid of dependency on Qt. Take care of Unicode management, there might be surprises. If everything is in UTF-8, std::string should work fine.

[jamiebullock]

You might want to look at boost.locale: http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/index.html

[sildeag]

Recently upgraded Gaia to work with Qt5.6 to Qt5.10 and Python2 or Python3 for Ubuntu 17.10. Backwards compatibility was maintained as much as possible. Unfortunately, getting rid of Qt would also involve getting rid of Cyclops too, if it worked, as it uses Qt Network.