first propper hoisting test

had to change course, normalising and object creation is not possible
in one go
have to now generate random tmp vars  that will have to be picked up
later (sorted by tmp_ prefix?)

lib/common/statements.rb

@@ -26,6 +26,7 @@ module Common
     end
     def <<(o)
       @statements << o
+      self
     end
     def collect(arr)
       @statements.each { |s| s.collect(arr) }