* Leaving out the script name means to read the script from standard
input. In this case the shebang line is _not_ handle -- simply
because I ran out steam. (Our shebang line processing assumes a
* Stream errors on standard streams cause scripts to exit silently.
* Scripts no longer us *TTY* for *TERMINAL-IO*, but make up a two-way
stream from *STDIN* and *STDOUT*. Similarly for *DEBUG-IO* but
using *STDERR*. This means that backtraces from errors are now
neatly captured in the standard error stream.