Where causing issues for people with MSVC.

Buffer var allocation coming into shape

Mozilla Bug 669175 - Slow rendering of text sometimes in this case,
using direction: rtl

While the cluster fields of the glyph string are usually sorted, they
wouldn't be in special cases (for example for non-native direction).
Blindly using bsearch is plain wrong.  If we want to reintroduce this
optimization we have to make sure we know the buffer clusters are
monotonic and in which direction.  Not sure it's worth it though.

Should be all set now.

Makes way for adding arbitrary user_data support.

This was a bizzare piece of API that I inherited from cairo.  It has
been wrong adding them to cairo in the first place.  Remove them before
someone uses them!

Returns the error status of the buffer.

The new name is self-documenting.

Return the length, whenever we return an array.  Makes it easier on the
language bindings.

This includes HB_DIRECTION_INVALID and HB_SCRIPT_INVALID.

The INVALID will cause a "guess whatever from the text" in hb_shape().
While it's not ideal, it works better than the previous defaults at
least (HB_DIRECTION_LTR and HB_SCRIPT_COMMON).

One should use hb_buffer_reset() really.

Reported on mailing list by Keith Stribley and Khaled Hosny.

We always allocate and grow str and pos together.