Implement String#chr
Implement String#chr for utf-8
Add test
Fix indents in mruby-string-utf8
Refactor mrb_utf8_strlen() in mruby-string-utf8
use is_a? Array for String#% argument check as the original PR did in #2349
Merge pull request #2350 from suzukaze/add-string.chr

Implement String#chr
Merge pull request #2351 from mattn/add-string-utf8.chr

Add string String#chr for utf8
Merge pull request #2353 from suzukaze/refactor-string-utf8

Refactor mrb_utf8_strlen() in mruby-string-utf8
Merge pull request #2352 from suzukaze/fix-indent

Fix indents in mruby-string-utf8
add dependency from mruby-string-utf8 to mruby-string-ext to ensure loading order
Add String#chars, String#each_char, String#codepoints, String#each_codepoint
arena save/restore
Refactor variable definitions
Add String#lines
Merge pull request #2356 from mattn/string-codepoints

Add String#chars, String#each_char, String#codepoints, String#each_codepoint
Merge pull request #2357 from mattn/string-lines

Add String#lines
fix String#lines comment; ref mattn@2e1855a
use pre-allocated RuntimeError for out-of-memory
indent ISO section comments