Bug#398193: combine: allow to compare only on a subset of the lines

[Spencer Bliven]

This is an old wishlist item, but I think it would make the combine utility
much better.

I suggest using the same parameter names as join for specifying fields to
compare.

       -t CHAR
              use CHAR as input and output field separator

       -1 FIELD
              join on this FIELD of file 1

       -2 FIELD
              join on this FIELD of file 2