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_ruby_block_statement.rb

@@ -25,22 +25,22 @@ module Ruby
       assert_equal 1 , @lst.body.arguments.length
     end
   end
-  class TestBlockStatementVool < MiniTest::Test
+  class TestBlockStatementSol < MiniTest::Test
     include RubyTests
 
     def setup()
       input = "plus_one{|arg1| arg1 + 1 } "
-      @lst = compile( input ).to_vool
+      @lst = compile( input ).to_sol
     end
     def test_block
-      assert_equal Vool::SendStatement , @lst.class
+      assert_equal Sol::SendStatement , @lst.class
     end
     def test_send_name
       assert_equal :plus_one , @lst.name
     end
     def test_send_block_arg
       assert_equal 1 , @lst.arguments.length
-      assert_equal Vool::LambdaExpression , @lst.arguments.first.class
+      assert_equal Sol::LambdaExpression , @lst.arguments.first.class
     end
     def test_block_args
       assert_equal [:arg1] , @lst.arguments.first.args