Handle Graphics Properties v0.1

So, I've codified the handle graphics properties that I think we need.

http://denney.homeip.net/octave/properties.html

This is definitely a work in progress.  I've borrowed liberally from 
Shai's props package (as suggested, though I have made changes where I 
thought that they were needed).  I've not really looked anywhere else yet, 
but this is what I think should be supported by most (if not all) graphics 
back ends.

I wrote this on the train while commuting during the past couple of days, 
and I plan to put it on the wiki soon (someone else can if they have 
time-- I won't have time for several days I don't think), but please start 
reading it, thinking about it, and discussing it.

As said, this is a work in progress, and I'd like to hear other opinions 
on what should be there, and how it should work.  There are some things 
that I agree and some that I disagree with Shai on (some are already 
changed, and some definitely need discussion).

The first thing that I'd like to discuss is:

Do we need separate patch and surface types, or can we just generalize the 
patch as a surface in the z=0 plane and remove the patch type (note that 
this doesn't mean removing the patch command)?

Bill

-- 
"I think animal testing is a terrible idea. They get all nervous and give
the wrong answers."
   -- A Bit of Fry & Laurie, British TV Series