User specific configuration may become invalid on upgrade (oldbug 5)

Created by: oskar-skog

The user specific configuration files obviously have a higher priority than the system wide.

The Makefile will not overwrite any configuration files unless manually requested. User specific configuration files cannot be overwritten during install.

Due to the lack of validity checking, potentially incompatible user configuration files will be loaded and the game will crash, most likely gracefully, with a KeyError exception.