i've been thinking on this refactoring since quite a bit of time. i'm moving the <override> traverser code to the usual java package. this doesn't change the correctness of current xerces <override> implementation.

git-svn-id: https://svn.apache.org/repos/asf/xerces/java/branches/xml-schema-1.1-dev@1565084 13f79535-47bb-0310-9956-ffa450edef68