- s/destroy/unref/  s/reference/ref/
- Add user_data (ryan wants array types!)
- enum script with tag values
- suger script from string
- s/hb_shape/hb_buffer_shape/
- mark buffer var members private
- hb_buffer_is_in_error()
- add out length to buffer array accessors
- rename add_glyph to add.  drop the mask?
- consider handling -1 as text/segment length
- y axis grows downward
- glib/icu two-way script mapping
- remove hb_buffer_clear()
- remove hb_buffer_clear_positions()
- s/hb_buffer_ensure/hb_buffer_pre_allocate/
- hb_ot_layout_position_start().  same for substitution, to do gdef init.

unicode:
- pass vtable, gunicode, user_data to the methods.

- user_data before destroy
- get_table changes

font:
- font should ref face, in create()
- font subclassing _derive?

blob:
- remove HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE possibly (survey fonts)