Split insert query during export when they exceed a configurable length

[nicolasriousset]

When exporting a large datebase, the generated insert sql statements may exceed the system limits. Trying to execute the query on MariaDB triggers the following error :
SQL Error (1153): Got a packet bigger than 'max_allowed_packet' bytes

Increasing the 'max_allowed_packet' value is a workaround, hower, adding an "insert size" limit, like in HeidiSQL, would be a better way to solve the issue by splitting the insert statement in several ones.

A default 0 value for this limit would keep the current behaviour.