PIG-3132: NPE when illustrating a relation with HCatLoader

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1460784 13f79535-47bb-0310-9956-ffa450edef68
Add license header for DOTParser.jjt

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1460797 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'trunk' of https://github.com/apache/pig into trunk