It's a simple, right-to-left, script.

Lao marks are center-aligned, unlike Thai ones.

Seems to produce more coherent results than trying the Indic shaper on
them.  I'm looking at you, Kh-* fonts...

This is important for the Sinhala U+0DDA split matra since it decomposes
to U+0DD9,U+0DCA where U+0DD9 is a left matra and U+0DCA is the virama.
We don't want to move the virama with the left matra.
TEST: U+0D9A,U+0DDA

Note that we were already doing this in the Uniscribe bug compatibility
mode.  We now do it all the time.

I don't expect anybody using hb_buffer_add(), so this shouldn't break
anyone's code.

Use with Arabic, for example, to see the effect on joining.

Ouch!

Ouch!

New API:

	hb_buffer_flags_t

	HB_BUFFER_FLAGS_DEFAULT
	HB_BUFFER_FLAG_BOT
	HB_BUFFER_FLAG_EOT
	HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES

	hb_buffer_set_flags()
	hb_buffer_get_flags()

We use the BOT flag to decide whether to insert dottedcircle if the
first char in the buffer is a combining mark.

The PRESERVE_DEFAULT_IGNORABLES flag prevents removal of characters like
ZWNJ/ZWJ/...

Ouch

Which is like _reset(), but does NOT clear unicode-funcs.

Had to do some refactoring to make this happen...

Under uniscribe bug compatibility mode, we still plit them
Uniscrie-style, but Jonathan and I convinced ourselves that there is no
harm doing this the Unicode way.  This change makes that happen, and
unbreaks free Sinhala fonts.

1. If there is any offset (x or y), print out both x and y offsets.

2. Always print out the advance in the major direction of the buffer.
Ie. even for zero-advance glyphs, print a "+0".  This is more intuitive.

Mostly affects Myanmar, but also Tai Tham, Javanese, and Cham.  The
latter three are untested (no fonts!).

Windows 8 adds a Myanmar shaper using the 'mym2' tag.  Route that
through the Indic shaper.  It's still very broken, but at least this
does NOT break old-style Myanmar shaping using the generic shaper.

For Arabic and Indic shapers, if the font doesn't have a script system
for the script, use default shaper.

Make an exception for Arabic script since we have fallback logic for
that one.

Windows 8 added support for Myanmar shaping using the "mym2" script tag,
even though Windows never supported the old "mymr" tag.