User profiles disabled

If an empty file with the name user_profiles_disabled is placed in the eduke32 base directory, the game will use this directory instead of Appdata or /home/user/.config/eduke32 to store user data.

This includes config files, screenshots, saves, the autoload directory and texture cache files. It also affects the commands readarrayfromfile and writearraytofile, which would normally also read/write data from/to the profile directory.

The presence of user_profiles_disabled is equivalent to setting the launch parameter -usecwd.