iBATIS Java discriminator/subMap support done

[Clinton Begin]

Thanks to what I think was a 5 hour movie (LOTR/ROTK), I've added the discriminator/subMap feature to iBATIS for Java.  Obviously inspired by our talented .NET team, this feature is committed to SVN and will be released with v.2.1.0.

Here's an example (similar to iBATIS.NET).

http://svn.apache.org/repos/asf/incubator/ibatis/trunk/java/mapper/mapper2/test/com/ibatis/sqlmap/maps/Documents.xml

Cheers,
Clinton