level dimension improvements

[Patrick M]

-level dimensions to be a globally applicable tool, not just slabs and meshes. why dont they work with walls? seems kind of basic there!

-level dimensions to have top, bottom, reference line links to: project 0, home story, levels, sea level

-level dimensions to have leader options (similar to other dimension types)

[Jerryjb]

Excellent Request.  This seems fundamental.