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

lib/ruby/basic_values.rb

@@ -1,7 +1,7 @@
 module Ruby
   class Constant < Statement
-    def to_vool
-      vool_brother.new
+    def to_sol
+      sol_brother.new
     end
   end
   class ValueConstant < Constant
@@ -9,8 +9,8 @@ module Ruby
     def initialize(value)
       @value = value
     end
-    def to_vool
-      vool_brother.new(@value)
+    def to_sol
+      sol_brother.new(@value)
     end
   end
   class IntegerConstant < ValueConstant