Rename Vool to Sol

Simple is really the descriptive name for the layer
Sure, it is "virtual" but that is not as important as the fact that it is simple (or simplified)
Also objct (based really) is better, since orientated implies it is a little like that, but only orientated, not really it. Sol only has objects, nothing else
Just cause i was renaming anyway

test/ruby/test_class_statement2.rb

@@ -9,18 +9,18 @@ module Ruby
     end
 
     def test_method_len
-      assert_equal 2 , @vool.body.length , "setter, getter"
+      assert_equal 2 , @sol.body.length , "setter, getter"
     end
     def test_setter
-      assert_equal Vool::MethodExpression , setter.class
+      assert_equal Sol::MethodExpression , setter.class
     end
     def test_setter_assign
-      assert_equal Vool::Statements , setter.body.class
-      assert_equal Vool::IvarAssignment , setter.body.first.class
+      assert_equal Sol::Statements , setter.body.class
+      assert_equal Sol::IvarAssignment , setter.body.first.class
     end
     def test_setter_return
-      assert_equal Vool::Statements , setter.body.class
-      assert_equal Vool::ReturnStatement , setter.body.last.class
+      assert_equal Sol::Statements , setter.body.class
+      assert_equal Sol::ReturnStatement , setter.body.last.class
     end
     def test_setter_name
       assert_equal :page= , setter.name
@@ -36,7 +36,7 @@ module Ruby
       "attr_reader :page"
     end
     def test_method_len
-      assert_equal 1 , @vool.body.length , "setter, getter"
+      assert_equal 1 , @sol.body.length , "setter, getter"
     end
 
   end