MC-TEMP-FILTER:  Copy only iterations at a given temperature.

MC-temp-filter copies records from an existing log file to a new log
file, keeping only those with negative indexes and those with the same
index as a simulated tempering ('b') record with a given index, or
optionally either the given index or an index of zero.

Usage:

   mc-temp-filter [ [-]temp-index ] input-log-file output-log-file 

If the temperature index is a positive integer, only records with that
temperature index are copied.  If the index is a negative integer,
those with the negation of that index and those with an index of zero
(highest temperature) are copied.  The default index is the biggest
one, associated with the lowest temperature.

The record indexes in the output file are resequenced to start at one,
with an increment of one.

The number of full tours from low to high temperature and back is
printed on standard error.

            Copyright (c) 1995 by Radford M. Neal