PIG-3591: Refactor POPackage
Review Request #15881 - Created Nov. 27, 2013 and updated
Separate "packaging" logic from "shuffle handling" logic. This moves the packaging logic to a new class "Packager", which is extended by CombinePackager, LitePackager, MultiQueryPackager, and JoinPackager. This is not finished. Known problem are illustrate and streaming the last input are not implemented.
ant test-commit passes, with the exception of TestExampleGenerator which is caused by the illustrate work not being finished. I also ran some manual scripts, which worked.