Improved Korean Grade 2 table contributed by Joseph Lee

This table includes support for reading English text using grade 2. This
was requested by Korean user and is documented in NVDA ticket
3835 (http://community.nvda-project.org/ticket/3835)

Korean users say that transcribers in Korea use grade 2 for English
texts for Korean grade 2.
Changed the license to LGPL

This was an oversight by the original author (see
http://www.freelists.org/post/liblouis-liblouisxml/Fwd-RE-Korean-grade-2-table-with-English-grade-2-support).
It was meant to be under the same license as the rest of the tables.
Added test cases
Merge branch 'tables/korean'

Thanks Joseph

Closes #5