The difference from CRuby's Encoding:
- Encoding is a module, instead of a class
- each Encoding (e.g. `Encoding::UTF_8) is a string instead of Encoding object
- only supports `UTF-8` and `ASCII-8BIT` (and its alias `BINARY`)
Using this gem automatically turn on `MRB_UTF8_STRING` support.
Yukihiro "Matz" Matsumoto