Fixes https://github.com/behdad/harfbuzz/issues/236
Fixes https://bugs.chromium.org/p/chromium/issues/detail?id=627953

Fixes https://bugs.chromium.org/p/chromium/issues/detail?id=614647
If allocation fails, we might be leaving junk behind.  At least
clear it up.

Prior to this change the function `FT_Error FT_Done_Face(FT_Face *)` was
called through a pointer with the signature `void (void *)` resulting in
undefined behaviour.

[introspection] Fix hb_tag_from_string annotation

Fixes https://github.com/behdad/harfbuzz/pull/271

Discard reconfigured CTFont if URL changes

Part of https://github.com/behdad/harfbuzz/issues/277

Revert "use utf32"

	[dwrite] Use stream font loader instead GDI interop

Addressing Nikolay Sivov reviews on harfbuzz mailing list

No longer noticeable memory increase on create/destroy iterations,
highly better than current state of uniscribe backend

This reduces memory consumption of my iterated font create/destroy cycle test
significantly and makes it much better than uniscribe backend even

With help of
https://dxr.mozilla.org/mozilla-central/source/gfx/2d/NativeFontResourceDWrite.cpp

Fix make check on Travis

The so-called Python 2 “narrow” builds support UCS2 only, this is a
workaround to allow unichr to work with any Unicode character in such
builds. This fixes Travis-CI failure as it has narrow Python 2 builds.

Copied from:
https://github.com/behdad/fonttools/blob/master/Lib/fontTools/misc/py23.py

Fixes https://github.com/behdad/harfbuzz/issues/267

Fixes https://github.com/behdad/harfbuzz/issues/255

That's where everything is happening these days.

Fixes https://github.com/behdad/harfbuzz/issues/218

From draft update to USE.

Fixes https://github.com/behdad/harfbuzz/issues/253

Hopefully we got the logic right.

Fixes https://github.com/behdad/harfbuzz/issues/243

With javatext.ttf, the reodering medial Ra gets its advance width
zero'ed in Uniscribe implementation, and the font adds the advance
back.  Our Indic shaper does not do that, but USE does.  So, route
Javanese through USE.  That's what Microsoft does anyway.  Test:

  U+A9A5,U+A9BA

This also seems to fix the following sequence, and variations thereof:

  U+A99F,U+A9C0,U+A9A2,U+A9BF