Graphite module not updated.
Bump version to 0.3.

Correspond to the make_mutable() ones.

One in particular is not a straight getter: hb_font_unset_funcs() is
special because of the specific needs of the lifecycle management of
the user_data object.

Got to add a suitable replacement.

hb_font_set_scale() now sets the value to be used to represent a unit
pixel.  For example, if rendering a 10px font with a 26.6 representation,
you would set scale to (10 << 6).  For 10px in 16.16 you would set it to
(10 << 16).  This space should be the same space that the get_glyph_metrics
and get_kerning callbacks work in.

Pointed out by Keith Stribley on HarfBuzz list.

To be in line with cairo

Not used yet.