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_macro_expression.rb

@@ -25,13 +25,13 @@ module Ruby
   class TestPlusEquals < Minitest::Test
     include RubyTests
     def setup
-      @lst = compile( "X.plus_equals(1)").to_vool
+      @lst = compile( "X.plus_equals(1)").to_sol
     end
     def test_class
-      assert_equal Vool::MacroExpression , @lst.class
+      assert_equal Sol::MacroExpression , @lst.class
     end
     def test_arg1
-      assert_equal Vool::IntegerConstant , @lst.arguments.first.class
+      assert_equal Sol::IntegerConstant , @lst.arguments.first.class
     end
     def test_name
       assert_equal :plus_equals , @lst.name
@@ -40,22 +40,22 @@ module Ruby
   class TestPlusEqualsX < Minitest::Test
     include RubyTests
     def setup
-      @lst = compile_main( "X.plus_equals(arg,1)").to_vool
+      @lst = compile_main( "X.plus_equals(arg,1)").to_sol
     end
     def method_body
       @lst.body.first.body
     end
     def test_class
-      assert_equal Vool::ClassExpression , @lst.class
-      assert_equal Vool::MethodExpression , @lst.body.first.class
+      assert_equal Sol::ClassExpression , @lst.class
+      assert_equal Sol::MethodExpression , @lst.body.first.class
     end
     def test_macro_class
-      assert_equal Vool::ReturnStatement , method_body.class
-      assert_equal Vool::MacroExpression , method_body.return_value.class
+      assert_equal Sol::ReturnStatement , method_body.class
+      assert_equal Sol::MacroExpression , method_body.return_value.class
     end
     def test_args
-      assert_equal Vool::LocalVariable , method_body.return_value.arguments.first.class
-      assert_equal Vool::IntegerConstant , method_body.return_value.arguments.last.class
+      assert_equal Sol::LocalVariable , method_body.return_value.arguments.first.class
+      assert_equal Sol::IntegerConstant , method_body.return_value.arguments.last.class
     end
     def test_name
       assert_equal :plus_equals , method_body.return_value.name