[HarfBuzz] stable-master merge

[Behdad Esfahbod]

Hi,

As you probably noticed I mostly finished merging my recent changes in
Pango with harfbuzz master, ie. Qt's.  When I started the patch between
the two versions was over ten thousand lines.  It's at about 900 lines
now and still shrinking.

Let me know if anything looks wrong.

Thanks,
-- 
behdad
http://behdad.org/

"Those who would give up Essential Liberty to purchase a little
 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759