make mom:method_compiler a list

Compilers forms alist by Util::CompilerList
Change Collection to use the list instead of array

test/rubyx/macro/helper.rb

@@ -5,12 +5,12 @@ module RubyX
     def setup
       whole ="class Space;def main(arg);return;end;end;" + source
       @mom = RubyXCompiler.new(RubyX.default_test_options).ruby_to_mom(whole)
-      @mom.method_compilers.first
+      @mom.method_compilers
       assert_equal Mom::MomCollection , @mom.class
       assert_equal Mom::MethodCompiler , compiler.class
     end
     def compiler
-      @mom.method_compilers.last
+      @mom.method_compilers.last_compiler
     end
 
   end