fix error with undefined similar in polygonize

[tiemvanderdeure]

polygonize calls similar on a Type and the abstractranges provided, but similar is not defined for all AbstractRange types.

I think the easiest fix is just to call length on the range first.

[asinghvi17]

Looks good, thanks! Do you have a test case that failed, so we can add it to the tests?

[tiemvanderdeure]

I just noticed there is a very similar PR that never got merged #190

Maybe this is not as simple as I thought?

[tiemvanderdeure]

I just went ahead and added tests, and let's see what happens.

I wanted to add a better test to make sure this returns the same polygon with different xs and ys like so:

    data_mp = polygonize(data)
    data_mp_range200 = polygonize(2:2:200, 2:2:200, data)
    data_mp_range200_2 = GO.apply(GI.PointTrait, data_mp_range200) do p
        p ./ 2
    end
    @test GO.equals(data_mp_range200_2, data_mp)

but this fails.