itrcfltr.icn: Program to filter trace output

This program filters trace output.  If there are command-line arguments,
they are taken as procedure names, and only those lines with those
names are written.  If there are no command-line arguments, all lines
are written.

The names of procedures to pass through can be given in a "response"
file as accepted by options(), as in

     itrcfltr @names <trace_file

where names is a file containing the names to be passed through.

The following option is supported:

     -a      list all trace messages; overrides any procedure names
               given