A "clear" method has been added to delete all data for a specific namespace (and profile).
Internal cache (self._cache) is not initialised with an empty dict instead of None to allow using methods like __setitem__ or clear without having to do a potentially expansive `load()` before. The only counterpart is that we won't have an exception anymore if developer forget to load() data before using them, which can make debugging a bit more difficult.
- moved directories from src and frontends/src to sat and sat_frontends, which is the recommanded naming convention
- move twisted directory to root
- removed all hacks from setup.py, and added missing dependencies, it is now clean
- use https URL for website in setup.py
- removed "Environment :: X11 Applications :: GTK", as wix is deprecated and removed
- renamed sat.sh to sat and fixed its installation
- added python_requires to specify Python version needed
- replaced glib2reactor which use deprecated code by gtk3reactor
sat can now be installed directly from virtualenv without using --system-site-packages anymore \o/