def read_global
      GLOBAL_CONFS.each { |gcf|
        if gcf.file? and gcf.readable?
          read gcf
          return
        end
      }
    end
def read_global
      GLOBAL_CONFS.each { |gcf|
        if gcf.file? and gcf.readable?
          read gcf
          return
        end
      }
    end
(Re)read the global prefs, if it exists.

 @return [void]