Fix ruby normalising to_vool

So that vool layer never has complex conditions or returns
Start with while, next if, return and assign

lib/vool/ivar_assignment.rb

@@ -2,6 +2,10 @@ module Vool
 
   class IvarAssignment < Assignment
 
+    def to_s(depth = 0)
+      "@#{super(depth)}"
+    end
+
     def to_mom( compiler )
       to = Mom::SlotDefinition.new(:message ,[ :receiver , @name])
       from = @value.slot_definition(compiler)

lib/vool/send_statement.rb

@@ -36,7 +36,6 @@ module Vool
     # - Setting up the next message, with receiver, arguments, and (importantly) return address
     # - a CachedCall , or a SimpleCall, depending on wether the receiver type can be determined
     def to_mom( compiler )
-      puts "Compiling #{self.to_s}"
       @receiver = SelfExpression.new(compiler.receiver_type) if @receiver.is_a?(SelfExpression)
       if(@receiver.ct_type)
         method = @receiver.ct_type.resolve_method(self.name)

lib/vool/statements.rb

@@ -33,6 +33,9 @@ module Vool
     def shift
       @statements.shift
     end
+    def pop
+      @statements.pop
+    end
 
     # to_mom all the statements. Append subsequent ones to the first, and return the
     # first.

lib/vool/while_statement.rb

@@ -14,6 +14,7 @@ module Vool
       cond_label = Mom::Label.new(self, "cond_label_#{object_id.to_s(16)}")
       codes = cond_label
       codes << @hoisted.to_mom(compiler) if @hoisted
+      codes << @condition.to_mom(compiler) if @condition.is_a?(SendStatement)
       codes << Mom::TruthCheck.new(condition.slot_definition(compiler) , merge_label)
       codes << @body.to_mom(compiler)
       codes << Mom::Jump.new(cond_label)