[hangul] Apply the appropriate *jmo features to decomposed syllables, including Old Hangul sequences that don't have Unicode compositions. Merge clusters in decomposed syllables.
[hangul] Reorder Hangul tone mark to beginning of syllable, unless font implements it using a zero-width glyph.
[unicode] Exclude the Jamo Filler characters from Default_Ignorable, as some fonts want these to be visible/spacing glyphs.
[hangul] Don't force zero-width for marks - this is not wanted for the Jamo Filler glyphs.
[hangul] Fix ordering of dotted circle with Hangul tone mark (reported by Dohyun Kim).
[ot] Don't try to compose if normalization is off
[arabic] Disable 'cswh' by default

I believe Windows 8 disables it, and spec update dated
Jan 2014 also clearly says it's disabled by default:

  http://www.microsoft.com/typography/OpenTypeDev/arabic/intro.htm#features
Fix typo in _hb_buffer_serialize_glyphs_text()

Fixes https://github.com/behdad/harfbuzz/pull/17
Fix clang warning 'private field 'xxx' is not used

Fixes https://github.com/behdad/harfbuzz/pull/16
Make it possible to disable the fallback shaper at configure time

The OT shaper supersedes the fallback shaper in every case
and the latter become an extra weight for 99.9% of users.
Micro optimizations
Fix double destruction in case of OOM
[coretext] Minor optimization
[coretext] Handle surrogate pairs when generating notdef glyphs

Fixes github.com/behdad/harfbuzz/pull/19
0.9.26
Improve MemoryBarrier() implementation

See thread "[HarfBuzz] compilation error of 0.9.26 with MinGW"
started by Werner.
typo in ucdn's Makefile.am
check hb_set_is_emtpy in test-set.c
Allow bootstrapping without gtk-doc

Seems like configure.ac is already able to handle it.
Only do fallback Hebrew composition if no GPOS 'mark' available

Apparently some modern fonts have proper GPOS mark positioning
tables, but undesirable precomposed forms!  See thread
"Hebrew composition to presentation forms" and:

  http://tex.stackexchange.com/questions/156775/having-trouble-with-vowel-positioning-in-ezra-sil-xelatex

Test case: U+fb1d,05d9,05b4