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