Limit calendar viewport scope

[MitMaro]

Have the various calendars on the site show only a fixed time frame (e.g. 7 a.m. - 8 p.m.) and have the remaining times show only with scrolling. Similar to the week view on Google Calendar.

[MitMaro]

Depends on #92.

[whymarrh]

Another option would be to allow each user to individually select their window, and times outside of that window (when matching) would not count (for #92). This way a parent could select from 7 a.m. to 7 p.m. and that would be both their viewport size and what we use when calculating schedule intersections.