Differentiate, using new attach_type().

No behavior change.  Preparing to unify how cursive and mark attachments
work.

Is confusing.  I already hit it myself.  Remove.  We can optimize
ASCII based on Unicode properties.  But should not do based on
assumptions on the font.

They had an invalid LookupFlag (32).

See thread at:
https://lists.freedesktop.org/archives/harfbuzz/2016-February/005462.html

Enable Build of HarfBuzz under Visual Studio using NMake Makefiles

Add into the NMake Makefiles to build the DirectWrite shaping backend,
but as PR #134 mentions, this is considered to be in an experimental state,
so don't include this in the build by default for now.  This is most probably
going to replace the Uniscribe backend eventually, since DirectWrite is meant
to be Uniscribe's replacement, and is needed for Windows Store apps if a
system shaping API is to be used.

This adds to the autotools build system so that the (experimental)
DirectWrite support for HarfBuzz is built (and dist'ed).

This adds a set of NMake Makefiles that can be used to build HarfBuzz, from
the standard basic build building the minimal HarfBuzz DLL (consisting
of OpenType, fallback and Uniscribe support only), to a full fledged build
consisting of GLib and FreeType support, as well as building the utilities,
the test programs in src/ and test/api, and HarfBuzz-ICU and
HarfBuzz-GObject, and up to building the introspection files.  This means a
flexible build mechanism is supported here, so anything that is supported
for a Windows build (code-wise), should all be supported by this build
system.

As in an earlier commit, the source listings are shared with the autotools
builds with the various Makefile.sources in src/, src/hb-ucdn and util/, and
this set of NMake Makefiles will transform these lists into the form they
want.

In the current form, all the test programs in test/api pass, and this has
been checked successfully with 'make -j8 distcheck'.

This adds a pre-configured config.h template that can be used for Visual
Studio builds, where autotools is not normally available.  This has the
configs that are suitable for Visual Studio builds, as well as all the
features used for Windows builds enabled (HAVE_OT, HAVE_FALLBACK and
HAVE_UNISCRIBE).

Note that the optional features are not enabled here, they are enabled by
/D's (or -D's) in the NMake Makefiles as requested.

This moves all the source listings in src/Makefile.am,
src/hb-ucdn/Makefile.am and util/Makefile.am into separate Makefile
snippets, so that they may be shared between different Makefile-based
build systems, such as NMake for Visual Studio.

Hopefully
fixes https://github.com/behdad/harfbuzz/issues/214

Add usermanual chapter on cluster levels

Refactor graphite2 to make ovleraps into negative width spaces

Fixes https://github.com/behdad/harfbuzz/issues/212

Very rudimentary right now, but will get kcc's bot going.

From
https://github.com/behdad/harfbuzz/issues/139#issuecomment-163580783

This speeds up shaping the Amiri font by over 15%.

This was primarily needed for my work on OpenType GX, since
we will be collecting only sublookups that are "active" for
current font instance; but it's a nice boost in general as
well.

We might, in the future, collect subtables in the lookup_accel.
That would also allow us to do a per-subtbale set-digest, which
should speed things up some more, specially for ContextChainFormat3
lookups...  Amiri, for example, contains one lookup with 53
subtables!

Fixes https://code.google.com/p/chromium/issues/detail?id=547912

Might add italic-angle, underline/strikethrough-position/thickness
in the future.  Do this before new struct goes into a release.

This happens with at least one test font I have.

See previous commit.

The font Garamond Premier Pro Caption (and possibly many other
Adobe fonts), have many FeatureParamsSize tables with the old
wrong offset.  We handle fixing those up, but they were still
contributing to edit_count, and when I reduced HB_SANITIZE_MAX_EDIT
from 100 to 8 in 14c2de32, these
fonts were now getting GPOS dropped and hence kerning disabled.

Fix, by not counting edits made towareds offset fix-up.  I'll
also increase edit count again, in the next commit.