Hidden line removal progress

 From:  Michael Gibson
6201.24 In reply to 6201.18 
Hi Burr,

re: generating hidden lines also in addition to visible lines.

> For me it would be nice to have access to these (as seperate object/sets as mentiond).

I think enough people have mentioned that they will occasionally use these that I'll try to have an option for making them, probably just unchecked by default.

- Michael