SpanMode uses incorrect terminology (breadth)

[Jesse Phillips]

On Monday, 17 September 2012 at 23:27:22 UTC, Ben Davis wrote:

> Note how the deeper you go, the more spread out the children 
> become. It's ALL children, then ALL grandchildren, then ALL 
> great-grandchildren, etc.
>
> I wouldn't bother implementing breadth-first. It's doubtful 
> that anyone would want it, surely...?

Ah sorry, yes. I didn't pay too close attention as I've never 
wanted to traverse a tree in that manner.

I'll update the title of the issue, add your comments.