Usage hack

dbohdan 2017-09-05: This is a tiny hack to accept command line arguments and display usage. You should probably use cmdline or autoopts instead.

> cat foo.tcl
proc [info script] {ip {port 22}} {
    # ...
}
[info script] {*}$argv
> ./foo.tcl
wrong # args: should be "./foo.tcl ip ?port?"