mruby/mruby — pull request #2616 by suzukaze (2014-10-20 13:52:13+00:00)
Title: Add Kernel#String

I ported to mruby from ruby:
rb_String(VALUE val)
https://github.com/ruby/ruby/blob/trunk/object.c#L3010

rb_check_string_type
https://github.com/ruby/ruby/blob/trunk/string.c#L1745

I fixed doc.

ruby
```
* Converts arg to a String by calling its
* to_s method.
```

mruby
```
* Returns arg as an String.
*
* First tries to call its to_str method, then its to_s method.
```