Idea: introduce alternate short syntax for script args

[dmiller-nmap]

Not sure this would work in all cases, but in some cases it might be nice. Example syntax:

nmap --script sample-script={arg=value}

Not sure whether this should coerce arg into sample-script.arg or not. Probably so, because if not, then we'd need a separate script arg environment for each script to avoid conflicts in cases like:

nmap --script sample-script={arg=1},another-script={arg=2}