1. Delete some unused imports.
2. Fix some of the types for enums so that they are publicly visible.
3. Perform a small optimization in the generated code (of javacc), so that the dreaded:
    if ("" != null) ...
    is only generated once for disjunctions in rules.  Unfortunately javac cannot optimize ("" != null) to true.
    I filed a bug with Oracle about this.  Hopefully it will be fixed.