Add support for multi-script languages

Some languages, such as uzn (Uzbek, northern) or uig (Uighur),
can be written in multiple scripts (resp. Latin, Cyrillic; Latin,
Arabic).

This update adds support for multiple UDHRs for one ISO-639-3,
and enables many by default (thus updating the default number of
supported languages to 175).

This however does not take into account how many speakers such a
declaration has.
Move spec/ to test/
Move benchmark/ to benchmark.js
Refactor benchmark
Update .npmignore
Refactor .gitignore
Refactor .jscs.json
Refactor bower ignore
Update changelog for 0.2.3
0.2.3