Implement ObjectSpace.each_object .
Use mrb_int.
Use mrb_int instead of int
REnv uses obj->c as env link; no super
Merge branch 'master' of github.com:mruby/mruby
Merge pull request #1937 from cubicdaiya/issues/mrb_int

Use mrb_int instead of int
use to_int to integer duck-type check