Add support for encoding only characters outside of the ASCII range

Useful before converting UTF-8 to other, potentially less compatible, encodings
Add support for encoding only characters outside of the ASCII range

Useful before converting UTF-8 to other, potentially less compatible, encodings

My intended use of this is to safely encode all non-ASCII characters in HTML output which may already contain HTML entities (thus I wish to avoid double-encoding) before converting from utf-8. Since entities encode to ASCII characters, the safest way to achieve this is to encode characters >255 as numeric entities.
Correction to README for new method
Merge pull request #5 from KeMBro2012/master

Add support for encoding only characters outside of the ASCII range