schema.sql: syntax fix
dashboard: fix typos in variable names
dashboard: fix ambiguous sql query
cleanup: check use of possibly undefined variable
cleanup: fix to avoid undefined array index warnings
dashboard: do not link directly to player scorecards

I found this desirable at one time, and I might want it again if
I publish read-only results online, but for now I don't want it.
tournament: add "use_teams" property
teams: add per-tournament switch to enable/disable Teams functionality
schema.sql: fix typo in the version 3 upgrade file
safety: throw error if query fails
bugfix: bad SQL query in contest.php
cleanup: avoid undefined-index warning
delete_venue: fix sql query based on old version of schema
cleanup: avoid cases of undefined indexes in contest.php