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/if_statement.rb

@@ -3,11 +3,11 @@ require_relative "normalizer"
 module Ruby
   # The if must have condition and a true branch, the false is optional
   #
-  # It maps pretty much one to one to a Vool, except for "hoisting"
+  # It maps pretty much one to one to a Sol, except for "hoisting"
   #
   # Ruby may have super complex expressions as the condition, whereas
-  # Vool may not. Ie of a Statement list all but the last are hoisted to before
-  # the vool if. This is equivalent, just easier to compile later
+  # Sol may not. Ie of a Statement list all but the last are hoisted to before
+  # the sol if. This is equivalent, just easier to compile later
   #
   # The hoisintg code is in Normalizer, as it is also useed in return and while
   class IfStatement < Statement
@@ -21,11 +21,11 @@ module Ruby
       @if_false = if_false
     end
 
-    def to_vool
-      cond , hoisted = *normalized_vool(@condition)
-      me = Vool::IfStatement.new(cond , @if_true&.to_vool, @if_false&.to_vool)
+    def to_sol
+      cond , hoisted = *normalized_sol(@condition)
+      me = Sol::IfStatement.new(cond , @if_true&.to_sol, @if_false&.to_sol)
       return me unless hoisted
-      Vool::Statements.new( hoisted ) << me
+      Sol::Statements.new( hoisted ) << me
     end
 
     def has_false?