Add Emoji data

**DO NOT MERGE!**

The data is still a DRAFT, but it wouldn’t hurt to have some code prepared that parses it correctly.

http://www.unicode.org/reports/tr51/index.html#Data_Files
http://www.unicode.org/reports/tr51/emoji-data.txt

Note: some emoji consist of multiple code points, so the resulting data structure can’t be a flat array of code points.

Ref. #17.