cut: diagnose a range starting with 0 (-f 0-2) as invalid, and

cut: diagnose a range starting with 0 (-f 0-2) as invalid, and
give a better diagnostic for a field-number/offset of 0.
* NEWS: Mention the fix.
* src/cut.c (ADD_RANGE_PAIR): Add an explicit check for 0.
Based on a patch from James Youngman.
* tests/misc/cut: Add tests for the above.