Convert Environment._Null from an old-style class to a new-style class.
Convert Environment._Null from an old-style class to a new-style class.

timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,timj/scons,timj/scons,timj/scons,andrewyoung1991/scons