Redo events organization

[ericthelemur]

I've had an idea to reorganize the events to be by week, which:

• simplifies the event page generation
• makes adding a new week by copying week to week easy
• removes the jank dependence on calls to the Tabula API (but maybe still?)
• means we can use relative dates (e.g. monday 6pm and more weirder stuff)
  • also relative event end times e.g. in 2 hours

[ericthelemur]

O