[Bf-python] Small omitted functions

[Stephen Swaney]

Campbell Barton wrote:
> 
> Heres the patch- pydocs added.

Committed.  Thanks.

Note: I changed the sense of the if() test, because it
would only decrement the user counts if a world didn't 
exist.

One thing I noticed testing this was that the Preview
panel in the World window would not get updated with
a complete redraw.  The rest of the world buttons seemed
ok.

This seems to be a blender issue, and not a bpy problem.
Switching to a different button window and back to World
refreshed the Preview.

-- 
Stephen Swaney			
sswaney at swbell.net