mysqli-rw split driver.

Added a new MySQLI-RW driver
Make sure you have two db-groups called "rw_write" and "rw_read"
and that the 'dbdriver' field is mysqli_rw

file: database.php
$db['rw_write']...
$db['rw_write']['dbdriver']='mysqli_rw'
...
$db['rw_read]...
$db['rw_read']['dbdriver']='mysqli_rw'

Use as you would normaly $db->query(...)
To force a read from write/master  use $db->query_from_master(...) instead.