Change Locals in calling convention

Just like the args, locals are now inlined into the Message.
Message is off course bigger, but as they are created at compile time, that hardly matters
Some programs did get somewhat smaller, especially with both changes, but not super much

lib/mom/method_compiler.rb

@@ -71,7 +71,9 @@ module Mom
       if index = @callable.arguments_type.variable_index(name)
         return ["arg#{index}".to_sym]
       end
-      [:frame , name]
+      index = @callable.frame_type.variable_index(name)
+      raise "no such local or argument #{name}" unless index
+      return ["local#{index}".to_sym]
     end
 
     def add_block_compiler(compiler)