Support 32-bit unsigned integers

On 32-bit builds, JS would see the wrong value when binding
constant like 0x80000000.
Don't return static undef to Perl

If the value ends up in hash/array, then it will be readonly.
Dispose of string_wrap and make_function.
Support latin1 keys in Perl hashes

- Conversion of e.g. "ä" would give "\ufffe" key because the
  passed string would have been invalid UTF8 string.