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

From http://www.babelstone.co.uk/Fonts/Marchen.html

So we are not relying on version of Unicode data in glib...

Fixes https://github.com/behdad/harfbuzz/issues/386
Fixes https://github.com/behdad/harfbuzz/issues/388

Android uses its own file these days and third-party developers should
be using the autotools-based system against Android NDK.

The decomposition is very obscure and unlikely to help
any fonts.  Just remove it since Uniscribe probably doesn't
do this either.

Fixes https://github.com/behdad/harfbuzz/issues/382

Part of https://github.com/behdad/harfbuzz/issues/382

This is now added to USE:
https://github.com/behdad/harfbuzz/pull/383

See:
https://github.com/behdad/harfbuzz/issues/381
https://github.com/behdad/harfbuzz/issues/382