Add support for Oracle's partition extension clause

[lukaseder]

For table partitioning, Oracle supports a "partition extension clause", which can be used with table references as such:

{ PARTITION (partition)
| PARTITION FOR (partition_key_value [, partition_key_value]..)
| SUBPARTITION (subpartition)
| SUBPARTITION FOR (subpartition_key_value [, subpartition_key_value]..)
}

This clause should be supported by jOOQ.

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As documented here:
http://docs.oracle.com/cd/E16655_01/server.121/e17209/sql_elements009.htm#i165979

As requested here:
https://groups.google.com/forum/#!topic/jooq-user/hLojif16pXM

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The partition feature is only available in Oracle Enterprise edition.