pg_dump multi VALUES INSERT

Hello,

According to the documentation –inserts option is mainly useful for making
dumps that can be loaded into non-PostgreSQL databases and to reduce the
amount of rows that might lost during error in reloading but multi values
insert command are equally portable and compact and also faster to reload
than single row statement. I think it deserve an option of its own

The patch attached add additional option for multi values insert statement
with a default values of 100 row per statement so the row lose during error
is at most 100 rather than entire table.

Comments?

Regards

Surafel