add support for non-BMP ligatures

add support for non-BMP ligatures

> http://www.unicode.org/versions/Unicode5.2.0/
D. Character Additions:
There are three new characters in the newly-encoded Kaithi script that will
require changes in implementations which make hard-coded assumptions about
composition during normalization. Most new characters added to the standard
with decompositions cannot be generated by the operations toNFC() or toNFKC),
but these three can. Implementers should check their code carefully
to ensure that it handles these three characters correctly.
U+1109A KAITHI LETTER DDDHA
U+1109C KAITHI LETTER RHA
U+110AB KAITHI LETTER VA

UCD 6.1 adds two more of them:
U+1112E CHAKMA VOWEL SIGN O
U+1112F CHAKMA VOWEL SIGN AU

Change-Id: I781a26848078d8b83a182b0fd4e681be2a6d9a27
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>