Read InnoDB Status from file before trying SQL

Reading innodb status information from file avoids the 64KB size
limitation imposed by the MySQL Storage Engine API.

The trade-off here is that you need to follow
http://dev.mysql.com/doc/refman/5.1/en/innodb-monitors.html in order to
enable InnoDB Monitor periodic file output.

I've implemented inteligence enough to enable MySQL.pm to determine if
the file is present and to prefer it to the SQL version of the innodb
status information.