Improve error message when using `intersect` instead of `intersect_interval`

[DimitriAlston]

If you run the following code:

using IntervalArithmetic
a = interval(1.0, 2.0)
intersect(a, a)

you would appropriately get the following error: ArgumentError: `intersect` is purposely not supported for intervals. See instead `intersect_interval` .
However, if you run something like this:

using IntervalArithmetic
a = interval(1.0, 2.0)
intersect(a, 1.0)

you would get: ArgumentError: `union!` is purposely not supported for intervals. See instead `hull` , but I believe this should return the same error as the first instance.

[OlivierHnt]

I agree that it is not ideal. I am not sure how to properly fix this in a clean way (and for other similar Julia functions) because there are many methods for intersect. I wonder in fact if this is more of an improvement that should be done in Julia Base itself.