I think we should take the substring parameters off al_draw_text() and
expose a version of it that takes a ustr instead. If you need to draw a
substring you can wrap it in a ustr quite easily.
void al_draw_text(const ALLEGRO_FONT *font, float x, float y, int flags,
const char *text);
void al_draw_ustr(const ALLEGRO_FONT *font, float x, float y, int flags,
const ALLEGRO_USTR *text);
The people who didn't like the count parameter should be happy as well
(that includes me after the count parameter became start/end).