msctl is now user-agnostic: any user can run the script in his
own account.
Default location is $HOME/mscs.
Default options can be overrided in config files $HOME/mscs.conf and
$HOME/.config/mscs/mscs.conf (first available file is used).
Command line config file override option (-c) is introduced, mainly
to support system-wide installation.
TODO: mscs wrapper to support system-wide installation and retain
backwards compatibility.