concatLogs()
ConcatLogs( $outstem, $odir, $curdir )
Concatenate the log files in $odir (./tmp_dir_*) to the ones in the main
working directory $curdir. (Output buffering should not be a problem,
because Log.pm opens and closes the files for each entry written.) The
file names all begin with $outstem. Removes the log files from $odir.