The testml script launches a newly-built and newly-linked
interactive system. It requires a previous run of the makeml
script because it uses the heap image 
. arch- osname
and libraries in .lib.
If no arguments are given, defaults to sml. If at least one
argument is given, then is assumed to be the first one. All other
arguments are passed to the initialization routine of the interactive
system just like normal arguments to the sml command would.
This means that one must specify a unless there are no
command-line arguments at all.