ofp-table: Better summarize table features and statistics.

ofp-table: Better summarize table features and statistics.

Before this patch, most dump-table-stats outputs would contain about
250 lines of the form:

  table #: ditto

With this patch, they have one line like this:

  tables 2...254: ditto

which is much easier to read.

Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>