Add ability to accommodate a student whose IEP specifies meeting once monthly

The current version of the scheduler outputs schedules that therapists repeat every week.

Ideas for workarounds, which will work with the current scheduler:

• If a student must be seen 30 minutes at a time once a month, enter it as if the student must receive 30 minutes of therapy each week.  Then, only invite the student to one of his/her scheduled weekly sessions each month.
• Enter all of your students who are seen weekly, then tell the scheduler to create your schedule for you.  When it's done, manually add your monthly-only students in the gaps that remain in your weekly schedule.

To properly implement this feature request, it would take some reworking, since the basic assumption is that the scheduler outputs a schedule that the therapist repeats weekly.  But we'll be happy to consider making the change if this request receives enough votes!