Some bugfixes, preliminary commit of relax_restrict_ip function. this
- adds relax_restrict_ip and hide_score_by_problem columns to the set
and set_user tables
- adds the corresponding fields to the Set and UserSet DB Records
- patches 'no location' handling in the location management routine
- improves Authz->checkSet's handling of the case of location
restriction when no addresses exist for a location, makes it
use any cached set that may be available, and makes it honor
- corrects a typo and some comments in DB.pm
- allows ip restriction fields in ProblemSetList when importing from
or exporting to set definition files
- updates ProblemSetDetail.pm to handle the relax_restrict_ip field
The relax_restrict_ip function has not been well tested.
hide_score_by_problem isn't yet used.