Great library, but I think there's a bug in the IntervalTree implementation. Consider the following snippet:

it = new IntervalTree()
it.add([10383734, 10594186])
it.add([9495571, 9677853])

it.add([9303743, 9404967])
it.intersects([9303743, 9303744])

This should logically return true, right? The intersection test clearly overlaps the last added interval. Running this, however, yields false. If either of the first two add statements are removed, the intersection check at the end returns true as expected.