1310aa04b4
This frees a byte value to use for 'end of key' (to correctly sort short keys) while still having a weight assigned to the field sep. (Unless -t is given, the field sep is in the field data.) Do reverse sorts by writing the output file in reverse order (rather than reversing the sort - apart from merges). All key compares are now unweighted. For 'sort -u' mark duplicates keys during the sort and don't write to the output. Use -S to mean a posix sort - where equal keys are sorted using the raw record (rather than being kept in the original order). For 'sort -f' (no keys) generate a key of the folded data (as for -n -i and -d), simplifies the code and allows a 'posix' sort.