Fix medicalsyncapi view for schema changes.
Improves filtering of Records

Adds a Record.filter() classmethod as a wrapper around
Record.objects.filter(). In addition to filtering by all the fields of
the Record model, it also accepts an optional bool parameter only_today,
which if True filters for Records only from the given day, which can be
useful for applications such as teacher check-in.

Modifies Record.user_completed() to also accept the only_today
parameter, and to use Record.filter() internally rather than construct
its own QuerySet.
Modifies teacher check-in to grant Records by day

Uses the new/improved Record.filter() and Record.user_completed()
methods to check for existing Records only for the given day.

Partially resolves Github issue #818.
Fixes multi-day teacher check-in

Only checkins from the date of 'when' (which defaults to the current
date) are considered, so that check-in can be reused each day/week of
the program. To see who failed to check in on a certain day / by a
certain time, admins can use the pre-existing "previous day" feature.

Resolves Github issue #818.
Sorts teacher check-in by time of class
Adds RecordTest class
Adds TeacherCheckinModuleTest

Starts by writing runCheckInTest(), which tests checkIn() and
undoCheckIn().

More tests forthcoming.
"not from this university" changed to "not currently enrolled at this university"

This makes the reporting of the answer to this question match the wording
of the original question.
Merge pull request #1176 from learning-unlimited/medicalsyncapi-schema-fixes

Medicalsyncapi schema fixes
Merge pull request #1212 from learning-unlimited/classreg-email-wording

Classreg email wording change
Merge pull request #1209 from learning-unlimited/issue-818

Issue 818
Merge branch 'main' into mit-prod