Attempting to fix Java IDL compilation incompatibilities with msgpack 0.4.0+

I've attempted to fix the various problems with IDL generation that prevent my IDL generated java code from running with msgpack 0.4.0+.

Unfortunately, I was unable to test this because A) it is 3 am and I'm tired and B) I'm not quite sure how to reinstall a test instance of msgpack IDL (maybe someone could help me on this?).

Anyone interested in continuing this work is more then welcome to do so. I would really like to see IDL generating Java that does not fail at runtime. Please PM me if you manage to get this working!