[chimera-dev] proxy support

[Eric Pettersen]

The development version of Chimera now has support for proxy web 
servers (controlled in the "Web Access" preferences category).  
Developers should try to use urllib.urlopen or urllib2.urlopen whenever 
possible rather than using httplib directly so that proxying will work 
without having to explicitly provide for it in your code.

                         Eric Pettersen
                         UCSF Computer Graphics Lab
                         pett at cgl.ucsf.edu
                         http://www.cgl.ucsf.edu