Add parameter to facilitate opening really big map files on machines with little RAM.
Add parameter to facilitate opening really big map files on machines with little RAM.

git-svn-id: d7bd6aa4c0dea6016ac69653009e6607750f5e02@169369 13f79535-47bb-0310-9956-ffa450edef68

toddlipcon/nutch,toddlipcon/nutch