Add Enumerable#zip
Support multiple values in Enumerable#zip
add String#oct
call to_a at the top of Enumerabl#zip; ref #1961
use __svalue instead of ary2sv
Enumerable#cycle to return enumerator
Enumerable#zip to use enumerator if mruby-enumerator gem is available
Merge pull request #1962 from cubicdaiya/feature/string_oct

add String#oct