The tt(run) member may immediately end if errors were encountered in the
specifications of the tt(Scanario) and/or tt(ConfigFile) parameters. 

One of the options defines the base directory into which the output is
written. The member tt(requireBase) checks whether the base directory exists,
and if not creates it. If that fails the program ends, showing the message
    verb(
    Cannot create base directory ...
    )
where tt(...) is replaced by the name of the base directory provided by the
tt(Options) object.

If all's well, the actual simulation is then performed by a tt(Loop) object.
