- Rename HB_SCRIPT_INVALID_CODE to HB_SCRIPT_INVALID
- Add HB_DIRECTION_INVALID
- Make hb_script_get_horizontal_direction() public
- Make hb_shape() guess script from buffer text (first non-common
non-inherit script) if buffer script is set to HB_SCRIPT_INVALID (this
is NOT the default.)
- Make hb_shape() guess direction from buffer script if buffer direction
is set to HB_DIRECTION_INVALID (this is NOT the default.)
- Make hb-view.c set INVALID script and direction on the buffer.
The above changes are meant to make hb-view fairly useful for uni-script
uni-direction text. The guessing behavior however is NOT the default of
hb_shape() and must be asked for explicitly. This is intended, because
the guess is not a suitable substitute to full-fledged bidi and script
segmentation. It's just a testing tool.