Correct duplicate SQL rows for cars

Q objects make for a complicated query that will return duplicate Car
objects (one per match on `filter`). The Q object could probably be
fixed, but adding a `DISTINCT` condition is a good enough fix.
Add summary for all trips (to be given to WIMP)

Add a WSC-viewable summary of all trips, with pertinent medical
information.

The WIMP view makes a large number of SQL queries. It could be improved
upon, but this page isn't heavily viewed, and it keeps the code simpler
to leave unoptimized.

As ensuring safety lecture attendance is the responsibility of leaders
and the WIMP, include a read-only lecture attendance field in tables.