OffsetInteger operations incorrect

[goretkin]

I think the intent of OffsetInteger is that it preserves all the structure of integers, but the definitions at

GeometryTypes.jl/src/faces.jl

Lines 26 to 35 in c42a2b3

	for op in (:(-), :abs)
	@eval $(op)(x::T) where {T <: OffsetInteger} = T($(op)(x.i))
	end
	for op in (:(+), :(-), :(*), :(/), :div)
	@eval begin
	@inline function $(op)(x::OffsetInteger{O}, y::OffsetInteger{O}) where O
	OffsetInteger{O}($op(x.i, y.i))
	end
	end
	end

don't do this.

The operations shouldn't happen on the underlying value, but on the "effective" value.

[SimonDanisch]

Hm good point... I will see if there are any regression by fixing this!

[goretkin]

Thanks for looking at the PR!