Log Message:
Update from version 1.5.1 (upstream 1.005001)  to version 1.6.0 (upstream
1.006000).

Pkgsrc changes:
- Canonize MASTER_SITES

Upstream changes:
1.006000 2010-03-31
        - Create lib::core::only that provides the "set @INC to core dirs
          only" functionality that was the only part of --self-contained that
          ever worked usefully.
        - Delete broken --self-contained flag from core