unify space collection attribute naming

currently space is still acting as a sort of memory manager.
For proper linking, all objects must be reachable from space, hence the plural versions like messages and addresses (even they are instances, it is the list that is important)
To dish out instance to use, the head must be kept, ie next_XXX for intergers, return addresses and messages

lib/parfait/space.rb

@@ -34,24 +34,27 @@ module Parfait
     def initialize( classes )
       @classes = classes
       @types = Dictionary.new
-      message = Message.new(nil)
-      101.times { @next_integer = Integer.new(0,@next_integer) }
-      10.times { @next_address = ReturnAddress.new(0,@next_address) }
-
-      50.times do
-        @first_message = Message.new message
-        message.set_caller @first_message
-        message = @first_message
-      end
       @classes.each do |name , cl|
         add_type(cl.instance_type)
       end
+      101.times { @integers = Integer.new(0,@integers) }
+      10.times { @addresses = ReturnAddress.new(0,@addresses) }
+      message = Message.new(nil)
+      50.times do
+        @messages = Message.new message
+        message.set_caller @messages
+        message = @messages
+      end
+      @next_message = @messages
+      @next_integer = @integers
+      @next_address = @addresses
       @true_object = Parfait::TrueClass.new
       @false_object = Parfait::FalseClass.new
       @nil_object = Parfait::NilClass.new
     end
 
-    attr_reader  :classes , :types , :first_message , :next_integer , :next_address
+    attr_reader  :classes , :types , :next_message , :next_integer , :next_address
+    attr_reader  :messages, :integers , :addresses
     attr_reader  :true_object , :false_object , :nil_object
 
     # hand out one of the preallocated ints for use as constant
@@ -68,7 +71,7 @@ module Parfait
     def get_address
       10.times do # 10 for whole pages
         @next_address = ReturnAddress.new(0,@next_address)
-      end unless @next_address
+      end unless @next_address.next_integer
       addr = @next_address
       @next_address = @next_address.next_integer
       addr