use OpenStruct instead of returning a hash value

When we created a Packet object before using
Packet.read would return a hash. Instead, return
an OpenStruct object which makes accessing
parameters easier

lib/X11/display.rb

@@ -5,6 +5,7 @@ module X11
   class AuthorizationError < X11Error; end
 
   class Display
+    attr_accessor :socket
 
     # Open a connection to the specified display (numbered from 0) on the specified host
     def initialize(target = ENV['DISPLAY'])
@@ -25,7 +26,7 @@ module X11
     end
 
     def screens
-      @internal[:screens].map do |s|
+      @internal.screens.map do |s|
         Screen.new(self, s)
       end
     end

lib/X11/packet.rb

@@ -50,7 +50,7 @@ module X11
             end
           end
 
-          values
+          OpenStruct.new(values)
         end
 
         def field(*args)
@@ -92,9 +92,7 @@ module X11
             s.type == :unused or s.type == :length
           end
         end
-
       end
     end
-
   end
 end

lib/X11/screen.rb

@@ -8,11 +8,15 @@ module X11
     end
 
     def width
-      @internal[:width_in_pixels]
+      @internal.width_in_pixels
     end
 
     def height
-      @internal[:height_in_pixels]
+      @internal.height_in_pixels
+    end
+
+    def to_s
+      "#<X11::Screen(#{id}) width=#{width} height=#{height}>"
     end
   end
 end