Provides an advanced configuration system

KConfig provides an advanced configuration system. It is made of two parts:
KConfigCore and KConfigGui.

KConfigCore provides access to the configuration files themselves. It features:

- centralized definition: define your configuration in an XML file and use
`kconfig_compiler` to generate classes to read and write configuration entries.

- lock-down (kiosk) support.

KConfigGui provides a way to hook widgets to the configuration so that they are
automatically initialized from the configuration and automatically propagate
their changes to their respective configuration files.