[Gtkradiant] [Bug 620] Add a Z Clipper tool like jk2 radiant

[gtkradiant@zerowing.idsoftware.com]

http://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=620





------- Additional Comments From jmonroe@ravensoft.com  2002-09-27 17:52 -------
Z Clipper is independent of regions. it is only used for view culling not bsp 
regions.

"We mainly used the z-clipper tool for aid in editing hugely vertical maps 
with many overlapping levels.

If we want a region (to bsp) of a specific area we just set a region 
manually.  The main attraction of the z-clipper is that we can drag its 
extents on the fly and se the new area we selected expand."