pd.Interval default closed='right'?
In my trying to use pd.Intervals/pd.IntervalIndex (which are terrific additions), I've become somewhat perplexed with the default of `closed='right'`. Python slicing is inclusive-exclusive, so I thought `pd.Interval`s might have the same default. I imagine there is a reason for this that I haven't quite understood.

I tried searching through the issue tracker for more information but wasn't really successful ... although I imagine it's pretty likely that I've missed the relevant issue.