hb_shape() now accepts a shaper_options and a shaper_list argument.
Both can be set to NULL to emulate previous API.  And in most situations
they are expected to be set to NULL.

hb_shape() also returns a boolean for now.  If shaper_list is NULL, the
return value can be ignored.

shaper_options is ignored for now, but otherwise it should be a
NULL-terminated list of strings.

shaper_list is a NULL-terminated list of strings.  Currently recognized
strings are "ot" for native OpenType Layout implementation, "uniscribe"
for the Uniscribe backend, and "fallback" for the non-complex backend
(that will be implemented shortly).  The fallback backend never fails.

The env var HB_SHAPER_LIST is also parsed and honored.  It's a
colon-separated list of shaper names.  The fallback shaper is invoked if
none of the env-listed shapers succeed.

New API hb_buffer_guess_properties() added.

Hardcoded to the uniscribe backend for now.  Will fix soon.

Where causing issues for people with MSVC.

Not complete yet, font selection doesn't work.  But hey it shapes!

This is not supposed to be a production backend, more like a testing
backend.

Need to think more about it.

Broke it a few commits ago.

(and revert change have_icu change I mistakenly pushed out)

With these changes, on Ubuntu I can do:

./configure --host=i586-mingw32msvc  && make

Read comment.

Not sure where this is documented, but I remember this being the desired
behavior.

test-shape-complex failures are down from 48 to 46.  Meh.

Not quite working just yet.  False alarm re 10 failures.  It was
crashing.  Ouch!  Back to 48 failures.

Not applied yet.

Brings test-shape-complex failures down from 52 to 10!

I hereby declare harfbuzz-ng supporting Indic!

But I'm not sure...  Down from 54 failures to 52.

In old-style Indic OT standards, the post-base Halants are moved after
their base.  Emulate that by moving first post-base Halant to
post-last-consonant.

Brings test-shape-complex failures down from 88 to 54.  Getting there!