LOG-APPEND:  Append records from one log file to the end of another.

Log-append takes certain records from one log file and appends them to
the end of another log file (which must already exist).  This is
useful for initializing iterative programs using the state from a
previous run.  It is also dangerous, however, as no check is made for
whether the records appended make sense in the new context.


   log-append input-log-file [ range ] output-log-file 

The records with indexes in the indicated range are read from
input-log-file and appended to the end of output-log-file.  The range
has the usual form of [low][:[high]][%modulus], as described in
parse_range in misc.c.  If high and the colon are omitted, high
defaults to low.  If high is omitted but the colon is present, the
range extends to the end of the file.  If no range is specified, it
defaults to the last index for which any records are stored.  Records
with negative indexes are never copied.

The records copied are appended to output-log-file, with consecutive
indexes starting after the index of the last existing record, at index
0 if only records with negative indexes are present.  In typical
usage, output-log-file will contain only specifications, with indexes
of -1, and the range to copy will consist of a single index.  In this
case, the records appended will have index 0, which is suitable for
initialization of an iterative program.

            Copyright (c) 1997 by Radford M. Neal