Hopefully also fixes build failure on msvc.

hb-view correctly renders variations with ft font-funcs now.
hb-ot-font needs HVAR implementation.

Is hooked up to the font, but not to FreeType, so raster doesn't show yet.

Documentation needs to be done.

Looks much better.

Supports enumerating variation axes, normalizing values, etc.

The numbers for right-to-left scripts are processed also from right to
left, so the order of applying “numr” and “dnom” features should be
reversed in such case.

Fixes https://github.com/behdad/harfbuzz/issues/395

Resolves https://github.com/behdad/harfbuzz/issues/324

Should be enough to get -hangul.cc out of SOURCES in Firefox build:
https://dxr.mozilla.org/mozilla-central/source/gfx/harfbuzz/src/moz.build

No one else should care!

We have had added this in Indic shaper to assist shaping these scripts.
In Universal Shaping Engine however, it is up to font designer to
decompose them.  Hence moving them from Indic shaper to USE was
wrong.

Fixup for f6ba63b2

Part of fixing https://github.com/behdad/harfbuzz/issues/387