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/statements.rb

@@ -35,11 +35,11 @@ module Ruby
       @statements << o
       self
     end
-    def to_vool
-      return first.to_vool if( single? )
-      brother = vool_brother.new(nil)
+    def to_sol
+      return first.to_sol if( single? )
+      brother = sol_brother.new(nil)
       @statements.each do |s|
-        brother << s.to_vool
+        brother << s.to_sol
       end
       brother
     end