psrsplit.icn: Program to separate psrecord.icn output pages

usage:  psrsplit file

   If a file produced by the procedures in psrecord.icn contains multiple
pages, it cannot be easily incorporated into another document.  psrsplit
reads such a file and breaks it into individual pages.  The algorithm
is frugal of memory and file descriptors at the expense of reading the
input file multiple times.

   For an input file is named xxxx or xxxx.yyy, the output files are
named xxxx.p01, xxxx.p02, etc. for as many pages as are available.
It is assumed that the input file was written by psrecord.icn; the
likelihood of correctly processing anything else is small.