Not that useful right now as we don't escape < and >.  Perhaps
another tool can be added to convert the ANSI output to HTML.

Patch and description from Jonathan Kew:

It turns out that some legacy Thai fonts provide OpenType substitution
features to implement mark positioning, but (incorrectly) put those
features/lookups under the 'latn' script tag instead of using 'thai' (or
possibly 'DFLT'). See
https://bugzilla.mozilla.org/show_bug.cgi?id=719366 for an example and
more detailed description.

Although this is really a font bug, I suggest that we could improve the
rendering of such fonts by looking for the 'latn' as a fallback if
neither the requested script nor "default" is found in
hb_ot_layout_table_choose_script. Suggested patch against harfbuzz
master is attached.

This does _not_ affect the other kind of legacy Thai font, where custom
code to support vendor-specific PUA codepoints would be needed. I'm not
keen to go down that path; IMO, such fonts should be ruthlessly stamped
out in favour of standards-based solutions. :)

JK

This means the --features indices also refer to char position
instead of byte position now.  Same for cluster values reported
by hb-shape.

Will add an option for byte indices later.

By bypassing readlines() buffering.

The actual utils are one-liners now.

New shaping testsuite and framework coming.

Imported from UTRRS.