ofp-print: Abbreviate duplicated table features.

ofp-print: Abbreviate duplicated table features.

I spent some time recently looking at the results of "ovs-ofctl
dump-table-features".  It was really distressing because of the volume of
information.  Every table yielded well over 100 lines of output and for 253
(visible) tables that meant over 25,300 lines of output total, which is
basically unusable.

This commit cuts the volume of output greatly by eliminating most of the
duplication from one table to the next.  The command now prints the full
output only for table 0, and for each subsequent table prints only the
parts that differ.  That reduces the output volume for tables after the
first to only 9 lines each (one of which is blank), for a total of more
like 2,400 lines, which is still not short but reasonably manageable.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>