Usage docs should explain how to use eventsThisInterval about clndr

[nk9]

I'd also point out that when you have a multi-day event which crosses a month boundary, the eventsThisInterval API returns it once for each month. While this does make sense, it's another thing to point out to users. And it would be nice to get some indication of this. If I only want a range event to show up once (say I'm showing a list of all the events in a given interval), the only way to ignore the month-straddling events at present is to keep a variable flag of whether it's been seen before. If the months returned were an object letting you know which month you were viewing, you could compare the start or end date of the event to the month to determine whether you wanted to display it.