Introduce singleton types

Just for future, as this gives us a way to know immediately in the type, which represent normal, and which singleton classes
Also instantiate singleton class lazily (with singleton type)
This makes the type of class single, ie unique, immediately when it is used, ie methods or variables defined.
Fixes a design mistake, where all singletonn classes shared the same type, and thus unique methods per class were impossible
(Also some misc in commit)

test/vool/class_send/test_send_class.rb

@@ -4,9 +4,25 @@ module Vool
   class TestSendClassMom < MiniTest::Test
     include VoolCompile
 
+    def class_main
+      <<-eos
+        class Space
+          def self.one_plus(one)
+            return 1 + 1
+          end
+        end
+        class Space
+          def main(arg)
+            return Space.one_plus(1)
+          end
+        end
+      eos
+    end
+
     def setup
-      @compiler = compile_main( "Object.get_internal_word(0)" , "Object.get" )
-      @ins = @compiler.mom_instructions.next
+      source = "class Integer < Data4;def +(other);X.int_operator(:+);end;end;" + class_main
+      ret = RubyX::RubyXCompiler.new(RubyX.default_test_options).ruby_to_mom(source)
+      @ins = ret.compilers.find_compiler_name(:main).mom_instructions.next
     end
 
     def test_array
@@ -37,10 +53,10 @@ module Vool
     def test_call_is
       assert_equal SimpleCall,  @ins.next(2).class
       assert_equal Parfait::CallableMethod,  @ins.next(2).method.class
-      assert_equal :get_internal_word,  @ins.next(2).method.name
+      assert_equal :one_plus,  @ins.next(2).method.name
     end
     def test_call_has_right_receiver
-      assert_equal "Class_Type",  @ins.next(2).method.self_type.name
+      assert_equal "Space.Single_Type",  @ins.next(2).method.self_type.name
     end
   end
 end