GitLab

(struct glyph): New member slice.
(GLYPH_SLICE_EQUAL_P): New macro.
(GLYPH_EQUAL_P): Use it.
(struct glyph_string): New member slice.
(struct it_slice): New struct.
(struct it): New member slice, add member to stack too.
New member constrain_row_ascent_descent_p.
(image_ascent): Add prototype.