Add Opera, Microsoft, and iCab to the contributors list

I propose we add the following contributors to the about:credits list:

   Opera Software Employees
   Microsoft Corporation Employees
   iCab Company Employees

We have copied many ideas from these people and it is only fair that we
credit them. (Ideas that come to mind are: Sidebar, DOCTYPE switching,
Text Zoom, defaulting to 96dpi on the Mac, Forms Autofill, Tabs, the Site
Navigation Toolbar, etc.)

-- 
Ian Hickson                                      )\._.,--....,'``.    fL
"meow"                                          /,   _.. \   _\  ;`._ ,.
http://index.hixie.ch/                         `._.-(,_..'--(,_..'`-.;.'