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_basic_values.rb

@@ -79,7 +79,7 @@ module Ruby
       assert_equal TrueConstant , compile_const( "true")
     end
   end
-  class TestBasicTypesVool < MiniTest::Test
+  class TestBasicTypesSol < MiniTest::Test
     include RubyTests
 
     def setup
@@ -87,7 +87,7 @@ module Ruby
     end
     def compile_const( input )
       lst = compile( input )
-      lst.to_vool.to_s
+      lst.to_sol.to_s
     end
     def test_integer
       assert_equal "123" , compile_const( "123")