src/cairo-array.c src/cairoint.h src/cairo-surface.c: Refactor user data code from cairo-surface.c into cairo_user_data_array_t.
Switch these types to be like cairo_surface_t where the generic code frees the wrapper object.
src/cairo-atsui-font.c src/cairo-ft-font.c src/cairo-win32-font.c: Fix up for the above changes.
Implement a complicated mutual-referencing scheme to make sure that a face from cairo_ft_font_face_create_for_ft_face() is freed only when the FT_Face is no longer needed.
Update the docs to describe how to figure out when the FT_Face can be freed.
Fix refcount leaks when creating fonts.
Remove excess call to _cairo_unscaled_font_reference().
Remove stray initialization of font matrix to the identity.
test/user-data.c: Fix a bug when setting/unsetting a key with a free key slot before it, add that to the test case.
Don't append an element when user_data is NULL.
Change type of 'surface' argument in show_glyphs to void * as it is for all other surface virtual functions.
Update accordingly.
Add check for endianess.
Fix bug in array growing loop. (_cairo_array_append): Accept NULL for elements argument, in which case we just allocate space in the array.
