Move vool block compilation into constant generation

When the lambda is passed as argument, it must be moved. This triggers the generation of a corresponding parfait object (as before, and as for other constants) but now also triggers the code build. The code being the constant as it were
Also some more name fixes from renames

lib/vool/send_statement.rb

@@ -10,12 +10,11 @@ module Vool
   # As cache key we must use the type of the object (which is the first word of _every_ object)
   # as that is constant, and function implementations depend on the type (not class)
   class SendStatement < CallStatement
-    attr_reader :block
 
     def block
       return nil if arguments.empty?
       bl = arguments.last
-      bl.is_a?(BlockStatement) ? bl : nil
+      bl.is_a?(LambdaExpression) ? bl : nil
     end
 
     def add_block( block )