Create min/max functions that take bounds into account

[morris25]

It would be nice to be able to get the first and last item within the bounds an Interval to some precision.
Ex.

julia> function min(i::Interval{T, Open}; precision=eps(T)) where T
       return first(i) + precision
end 

julia> function min(i::Interval{T, Closed}; precision=eps(T)) where T
       return first(i)
end

julia> min(Interval{Open, Open}(1.0, 2.0); precision=0.1)
1.1

julia> min(Interval{Closed, Closed}(1.0, 2.0); precision=0.1)
1.0

[nickrobinson251]

xref #90 (comment)