Hosting plot demos

[Pantxo Diribarne]

Hi,

I'd like to start tracking regression in the graphics/printing system 
ahead of Octave 6.1 release. For this we need to run plot demos and make 
them available on a central place.

Andy, since you have "traditionally" hosted the plot demo comparison 
pages on your server, I took the liberty to cc you directly, in case you 
would accept to continue.

Or better, if we could have a dedicated page, this would avoid relying 
on a private server.


Pantxo