Introduce IntervalType for union of Interval and BareInterval

[dpsanders]

In packages like IntervalConstraintProgramming I often need to refer to the Union of Interval and BareInterval. Currently I need to define that union in each package.

I propose to export

const IntervalType{T} = Union{Interval{T}, BareInterval{T}}

from IntervalArithmetic.jl.

[OlivierHnt]

That sounds reasonable. One note: we export the aliases

const RealOrComplexI{T} = Union{Interval{T},Complex{Interval{T}}}
const ComplexI{T} = Complex{Interval{T}}

So maybe the naming IntervalType is misleading as it does not include ComplexI. Maybe

const RealIntervalType{T} = Union{BareInterval{T},Interval{T}}

is less ambiguous? Or do you have an other suggestion?

[dpsanders]

Ah I didn't realise that, thanks.
Yes RealIntervalType sounds good. Or just RealInterval?