close #21

Mostly replaced Fixnum with integer
also in the rx-file dependency
all travis and testing with 2.4+

test/mains/test_new.rb

@@ -10,7 +10,7 @@ module Mains
     end
     def test_chain # max 1011 iterations on 1014 integers (1024 - 10 reserve)
       run_all
-      assert_equal Fixnum , get_return.class , " "
+      assert_equal ::Integer , get_return.class , " "
       assert_equal 0 , get_return , " "
     end